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Curso completo de Desenvolvimento Web Crie 6 projetosHTML JAVASCRIPT CSS PHP 8. Bootstrap - Criando Sites Responsivos 14. Botões - (Arquivos da aula)

Curso completo de Desenvolvimento Web Crie 6 projetosHTML JAVASCRIPT CSS PHP 18. Extras 1. Salvar Automaticamente no Sublime Text (Bônus)

The panelists talk about refactoring JavaScript Apps Into a Framework with Brandon Hays.

The panelists discuss whether HTML5 and JavaScript can really replace Flash.

Curso completo de Desenvolvimento Web Crie 6 projetosHTML JAVASCRIPT CSS PHP 8. Bootstrap - Criando Sites Responsivos 38. Spotify - Criando área de conteúdos - Parte I

Curso completo de Desenvolvimento Web Crie 6 projetosHTML JAVASCRIPT CSS PHP 16. Ajax (Asynchronous Javascript and XML) 5. Requisições síncronas com links

Curso completo de Desenvolvimento Web Crie 6 projetosHTML JAVASCRIPT CSS PHP 15. MySQL 3. Utilizando o PHPMyAdmin para manipulação do MySQL

Curso completo de Desenvolvimento Web Crie 6 projetosHTML JAVASCRIPT CSS PHP 9. JavaScript 32. Projeto final - Game estourando balões - parte 1

Curso completo de Desenvolvimento Web Crie 6 projetosHTML JAVASCRIPT CSS PHP 12. PHP 23. Estruturas de repetição - parte 3 de 5 do while

Curso completo de Desenvolvimento Web Crie 6 projetosHTML JAVASCRIPT CSS PHP 17. PHP & MySQL - Projeto aplicado Twitter Clone 15. Cadastro de usuário - Bloquear inclusão de usuários já cadastrados parte 1

This file was stored at "C:\Users\user\Documents\file-to-base64.html" Your web browsers needs to have JavaScript enabled in order for this to work. Complete source code of HTML file "file-to-base64.html": < !DOCTYPE html > < html lang="en" > < head > < meta charset="utf-8" / > < title > File to Base64 with JavaScript in 400 characters < /title > < /head > < input type="file" / > < p id="out" > < /p > < script > var input = document.querySelector('input[type=file]'); input.onchange = function () {   var file = input.files[0],   reader = new FileReader();     reader.onloadend = function ()     {       var b64 = reader.result       .replace(/^data:.+;base64,/, ''); /*comment out this line for Base64 as a data URI*/       document.getElementById("out").innerHTML = b64;     };   reader.readAsDataURL(file); }; < /script > < /html > Sources: * Add where I got the code from, which I later modified [done - no] * 400 characters inside the script tag, according to https://thewordcounter.com/character-counter/ * Valid HTML according to https://validator.w3.org/nu/#file

Big Microsoft's Xbox One Update

Video content can be found here: https://www.youtube.com/channel/UC0BAd8tPlDqFvDYBemHcQPQ/

Curso completo de Desenvolvimento Web Crie 6 projetosHTML JAVASCRIPT CSS PHP 5. CSS Intermediário 1. O que irei aprender nesse módulo

Curso completo de Desenvolvimento Web Crie 6 projetosHTML JAVASCRIPT CSS PHP 15. MySQL 18. Junções entre tabelas

JavaScript Jabber celebrates its 400th episode with former host Dave Smith and some other familiar voices. Each of the panelists talks about what they’ve been up to. Dave hasn’t been on the show for 3 years, but he and Jameson Dance have started a podcast called Soft Skills Engineering where they answer questions about the non-technical side of engineering. When he left the show he was the director of engineering on Hire View, and currently he works for Amazon on Alexa.  Christopher Buecheler has been on several JSJ, RRU, and MJS episodes. His time is divided between contracting for startups and his own company closebrace.com, a tutorial and resource site for JavaScript developers.  Dan Shapir has also been on JSJ as a guest, and is currently works for Wix doing performance tech. He enjoys speaking at conferences, such as JS Camp in Bucharest, Romania and the YGLF conference. Steve Edwards was previously on MJS 078. He started on Drupal in the PHP world, switched to JavaScript, and then a few years ago he started looking at Vue. Now he does Vue fulltime for ImageWare Systems. As for Charles, his primary focus is the podcasts, since DevChat.tv produces around 20 episodes per week. 5 new shows were started in July, and he talks about some of the challenges that that brought. One of his most popular shows recently was JSJ 389: What makes a 10x Engineer? This helped him realize that he wants to help teach people how to be a successful engineer, so he’s working on launching a new show about it.  The panelists share some of their favorite JSJ episodes. They discuss the tendency of JSJ to get early access to these fascinating people when the conversation was just beginning, such as the inventor of Redux Dan Abramov, before their rise to stardom. The talk about the rise in popularity of podcasting in general. They agree that even though JavaScript is evolving and changing quickly, it’s still helpful to listen to old episodes.  Charles talks about the influence JavaScript Jabber has had on other podcasts. It has spawned several spinoffs, including My JavaScript Story. He’s had several hosts start their own DevChat.tv shows based off JavaScript Jabber, including Adventures in Angular and The DevEd Podcast. JavaScript Jabber has also been the inspiration for other podcasts that aren’t part of DevChat.tv. There aren’t many podcast companies that produce as many shows as they do and they’re developing their own tools. DevChat.tv moved off of WordPress and is in the process of moving over to Podwrench. Charles talks about all the new shows that have been launched, and his view on ‘competing’ podcasts. Charles is also considering doing an audio drama that happens in a programming office, so if you would like to write and/or voice that  show, he invites you to contact him.  The show concludes with the panel talking about the projects they’ve been working on that they want listeners to check out. Christopher invites listeners to check out closebrace.com. He also has plans to write a short ebook on unit testing with jest, considered doing his own podcast, and invites people to check out his fiction books on his website. Dan talks about his involvement with Wix, a drag and drop website service, that recently released a technology called Corvid which lets you write JS into the website you build with Wix. This means you can design your user interface using Wix, but then automate it, add events functionality, etc. Dan is also going to be at the Chrome Dev Summit conference. Dave invites listeners to check out the Soft Skills Engineering podcast, and Charles invites listeners to subscribe to his new site maxcoders.io.  Panelists ? ? Dan Shapir ? ? ? Christopher Buecheler ? ? ? Steve Edwards ? ? ? Dave Smith ? ? ? Charles Max Wood ? Sponsors ? ? Tidelift ? ? ? Sentry use the code “devchat” for 2 months free on Sentry’s small plan ? ? ? Adventures in .NET ? Links ? ? The Dev Rev ? ? ? MJS 099: Christopher Buecheler ? ? ? JSJ 338: It's Supposed to Hurt. Get Outside of Your Comfort Zone to Master Your Craft with Christopher Buecheler ? ? ? RRU 029: Christopher Buecheler Getting Ready to Teach Lessons Learned from Building an 84 Tutorial Software Course ? ? ? MJS 108: Dan Shapir ? ? ? JSJ 334: Web Performance API with Dan Shapir ? ? ? JSJ 371: The Benefits and Challenges of Server Side Rendering with Dan Shapir ? ? ? MJS 078: Steve Edwards ? ? ? JSJ 179: Redux and React with Dan Abramov ? ? ? JSJ 187: Vue.js with Evan You ? ? ? JSJ 383: What is JavaScript? ? ? ? JSJ 385: What Can You Build with JavaScript ? ? ? JSJ 390: Transposit with Adam Leventhal ? ? ? JSJ 395: The New Ember with Mike North ? ? ? JSJ 220: Teaching JavaScript with Kyle Simpson ? ? ? JSJ 313: Light Functional JavaScript with Kyle Simpson ? ? ? JSJ 124: The Origin of JavaScript with Brendan Eich ? ? ? JSJ 073: React with Pete Hunt and Jordan Walke ? ? ? JSJ 392: The Murky Past and Misty Future of JavaScript with Douglas Crockford ? ? ? JSJ 391: Debugging with Todd Gardner ? ? ? JSJ 389: What Makes a 10x Engineer? ? ? ? cwbuecheler.com  ? ? ? Closebrace.com ? ? ? Corvid by Wix   ? ? ? Soft Skills Engineering podcast ? ? ? maxcoders.io                                                                                                                                                                            ? Follow DevChatTV on Facebook and Twitter Picks Steve Edwards: ? ? form.io ? Christopher Buecheler: ? ? Apollo GraphQL Playground ? ? ? @TheTimeCowboy Jake Lawrence ? Charles Max Wood: ? ? St. George Marathon ? ? ? GU Energy Original Sports Nutrition Energy Gel ? ? ? Vrbo ? ? ? devchat.tv/15minutes ? Dan Shapir: ? ? Revolutions by Mike Duncan podcast ? ? ? The Winter of the World book series ? Dave Smith: ? ? 13 Minutes to the Moon podcast by BBC ? ? ? The Mind ?

On today's episode, Charles, Joe, and Cory discuss  Practical JavaScript with Gordon Zhu . Gordon is the founder of Watch and Code, and teaches the Practical JavaScript online course. His mission is to help beginners become developers through tutorials. Tune in!

The panelists discuss The New York Times and JavaScript with Eitan Konigsburg, Alastair Coote and Reed Emmons.

In today's all-panelist episode, we take a deep dive into some of the nooks and crannies of JavaScript. We discuss and debate the benefits and problems of various methods such as getter and setter, Const, Freeze and Proxy. SponsorsTop End DevsRaygun | Click here to get started on your free 14-day trialCoaching | Top End DevsPicksAJ - Valley Forge FlagsAJ - Frog ChessAJ - Beyond Code BootcampAJ - Creeds of CraftsmanshipDan - JSConf BudapestDan - Stock Market / Tech Stocks going downDan - War in UkraineSteve - Dad JokesSponsored By:Coaching | Top End Devs: Do you want to level up your career? or go freelance? or start a podcast or youtube channel? Let Charles Max Wood Help You Achieve Your DreamsRaygun: Raygun now offers Real User Monitoring of Core Web Vitals. Start your 14-day free trial now.Top End Devs: Learn to Become a Top 5% Developer. Join our community of ambitious and engaged programmers to learn how.

Steve and AJ talk with Max Kordek, founder of his startup Lisk, which is geared towards helping JavaScript developers use the blockchain to develop new applications for new industries. We delve deep into the origins and base technologies of the blockchain, how it has been used, and how it can be used in the future. They also discuss Lisk, it's purpose, and how Max hopes their SDK will be used by developers to explore the blockchain and find brand new applications for it.PanelAJ O'NealSteve EdwardsGuestMax KordekSponsorsDev Influencers AcceleratorRaygun | Click here to get started on your free 14-day trialPodcastBootcamp.ioLinksGitHub | LiskHackonLiskLiskMastering blockchain: Meet Lisk, a blockchain platform for JavaScript developersBlog Archives | LiskIntroducing the Lisk Grant ProgramThe 5th Anniversary of Lisk NetworkIntroducing Lisk Interoperability - YouTubeLisk International - YouTubeEvents - YouTubeLisk - DiscordLisk CommunityLisk - RedditLisk - YouTubeTwitter: Lisk ( @LiskHQ )Max Kordek - YouTubeTwitter: Max Kordek | HODLing the Lisk Gem ( @maxkordek )PicksAJ- Blockchain Backer on TeachableAJ- Blockchain Backer - YouTubeAJ- HashcashAJ- Cryptocurrency is an abject disasterAJ- Nyan Cat NFTAJ- Walmart urges its suppliers to use IBM blockchain technologyAJ- Ep. 139 - Smart Contracts & Oracles - insights from ChainlinkMax- Technology | NASAContact AJ:AJ ONealCoolAJ86 on GITBeyond Code BootcampBeyond Code Bootcamp | GitHubFollow Beyond Code Bootcamp | FacebookTwitter: Beyond Code Bootcamp ( @_beyondcode )Contact Steve:Twitter: Steve Edwards ( @wonder95 )GitHub: Steve Edwards ( wonder95 )LinkedIn: Steve EdwardsSpecial Guest: Max Kordek.Sponsored By:Podcast Bootcamp: Launch an Amazing Sounding Podcast in just 4 WEEKS! Work with a 13 year podcasting veteran to get your podcast started off on the right foot! Raygun: Raygun now offers Real User Monitoring of Core Web Vitals. Start your 14-day free trial now.

Curso completo de Desenvolvimento Web Crie 6 projetosHTML JAVASCRIPT CSS PHP 17. PHP & MySQL - Projeto aplicado Twitter Clone 16. Cadastro de usuário - Bloquear inclusão de usuários já cadastrados parte 2

Curso completo de Desenvolvimento Web Crie 6 projetosHTML JAVASCRIPT CSS PHP 8. Bootstrap - Criando Sites Responsivos 21. Glyphicons - Ícones (Arquivos da aula)

Curso completo de Desenvolvimento Web Crie 6 projetosHTML JAVASCRIPT CSS PHP 13. Funções PHP 7. Funções básicas - Validação de formulários

Curso completo de Desenvolvimento Web Crie 6 projetosHTML JAVASCRIPT CSS PHP 9. JavaScript 21. Eventos - Introdução

Curso completo de Desenvolvimento Web Crie 6 projetosHTML JAVASCRIPT CSS PHP 14. Orientação a objetos PHP 7. Calculadora (Projeto final)

Curso completo de Desenvolvimento Web Crie 6 projetosHTML JAVASCRIPT CSS PHP 14. Orientação a objetos PHP 7. Calculadora (Projeto final)

Curso completo de Desenvolvimento Web Crie 6 projetosHTML JAVASCRIPT CSS PHP 10. JQuery 9. Projeto final - Jogo da velha - introdução

Curso completo de Desenvolvimento Web Crie 6 projetosHTML JAVASCRIPT CSS PHP 3. HTML 2. O que é HTML

Curso completo de Desenvolvimento Web Crie 6 projetosHTML JAVASCRIPT CSS PHP 3. HTML 15. Formulários

Video content can be found here: https://www.youtube.com/channel/UC0BAd8tPlDqFvDYBemHcQPQ/

Video content can be found here: https://www.youtube.com/channel/UC0BAd8tPlDqFvDYBemHcQPQ/

Today in this all panelist episode, we talk about JS features you should avoid using. However opinions don't always align, and some come with much debate! Although we couldn't cover them all, today we discuss:eval withargumentsdo while for I++continue classesprototypesthisvar with letdeleteSponsorsTop End DevsRaygun | Click here to get started on your free 14-day trialCoaching | Top End DevsLinksJavaScript Remote Conference 2022Twitter: ?@cmaxwPicksAJ- Virginia Ctenucha Ctenucha virginica (Esper, 1794) | Butterflies and Moths of North AmericaAJ- The Mistborn Trilogy by Brandon SandersonAJ- Thread pitch gauge at Lowes.com: Search ResultsCharles- AntidoteCharles- Conferences | Top End DevsCharles- 1883 - Yellowstone Prequel (Official Site) Watch on Paramount+Dan- Can I use... Support tables for HTML5, CSS3, etcDan - War in UkraineDan- Webb Space Telescope GSFC/NASASteve- Coworker Standing At Desk Obviously Just Hasn't Learned About Chairs YetSteve - Dad Jokes

マツイさん(circled9) をゲストにお迎えしてJavaScriptのテストやダイエットについてお話していただきました

The panelists discuss testing JavaScript with Joe Eames

Use this link and code JAVAJAB to get 20% off your registration for FluentConf 2013!Panel?David Herman (twitter blog Effective JavaScript)?Ariya Hidayat (twitter github blog)?Tim Caswell (twitter github howtonode.org)?Jamison Dance (twitter github blog)?Joe Eames (twitter github blog)?Merrick Christensen (twitter github)?Charles Max Wood (twitter github Teach Me To Code Rails Ramp Up)Discussion00:48 - David Herman and Ariya Hidayat Introduction?044 JSJ Book Club: Effective JavaScript with David Herman?023 JSJ Phantom.js with Ariya Hidayat01:54 - Parsing JavaScript and ASTs and Language Grammars04:44 - Semantics06:08 - Abstract Syntax Tree (AST)?Esprima: Parser?SpiderMonkey10:37 - Lexer12:16 - Writing your own language?creationix / jack?The C Programming Language17:41 - Parser Generators?JavaScriptCore21:04 - Evolving a SyntaxAutomatic Semicolon Insertion?Post correspondence problem?Halting problem28:05 - Language Design?The Rust Programming Language30:35 - Grammar?Regular Expressions (Regex)?Backus-Naur Form (BNF)?Recursion?How to Design Programs (HTDP)38:00 - Recursive Descent Parsers42:48 - Benefits of knowing language internals and syntax?Apache Lucene - Apache Lucene Core?LPeg - Parsing Expression Grammars For Lua48:48 - Abstract Syntax Tree (AST)Picks?Mass Effect 3 (Joe)?A Beginner's Guide to Irrational Behavior | Coursera (Joe)?Go write a programming language to learn one (Tim)?Thumbs and Ammo (Jamison)?ISM by Savant (Jamison)?Vimcasts (Jamison)?The iPhreaks Show (Chuck)?Mozy (Chuck)?Tech & Go Bright Pink Micro USB Cable (David)?asm.js (David)?Beyond Office Politics: The Hidden Story of Power, Affiliation & Achievement in the Workplace by Linda Sommer (Ariya)?gotwarlost / istanbul (Ariya)Next WeekWeb Developer SkillsTranscriptJAMISON: I am Linus Torvalds and I pronounce Linux, Linix.[Hosting and bandwidth provided by the Blue Box Group. Check them out at Bluebox.net.][This episode is sponsored by Component One, makers of Wijmo. If you need stunning UI elements or awesome graphs and charts, then go to Wijmo.com and check them out.]CHUCK: Hey everybody and welcome to Episode 54 of the JavaScript Jabber Show. This week on our panel, we have Tim Caswell.TIM: Hello.CHUCK: Jamison Dance.JAMISON: Hi guys.CHUCK: Joe Eames.JOE: Hey there.CHUCK: Merrick Christensen.MERRICK: Hey guys, what's up?CHUCK: I'm Charles Max Wood from DevChat.tv. And we have two special guests this week. We have Dave Herman.DAVID: Hey there.CHUCK: Ariya Hidayat.ARIYA: Hello everyone.CHUCK: And these guys are so smart that we brought them back. So, if you're interested, we'll put links to the episodes that they were on. David was on when we talked about his book 'Essential JavaScript' and Ariya was on when we talked about PhantomJS.JAMISON: Effective JavaScript.CHUCK: Effective? What did I say?MERRICK: Essential.CHUCK: Essential? Well, it's an essential book on Effective JavaScript. How's that?[Laughter]MERRICK: Good save.DAVID: At least, you didn't say Defective JavaScript.[Laughter]CHUCK: No, that's what I write. I'm really good at writing defective JavaScript.ARIYA: Actually, there's a book about Essential on Defective JavaScript.CHUCK: I also want to announce really quickly that Fluent Conf has given us a discount code. So, if you want to get 20% off on your registration for Fluent Conf, just enter JAVAJAB and you'll get 20% off when you register for Fluent Conf.Alright. Well, let's get started. This is going to be a really, really interesting topic and it's something that I've wanted to know more about for a long time. And I just haven't delved as deeply into it as I would like to. And that is,

Our very own Will Button from Adventures in DevOps joins us to discuss DevOps in JavaScript. Will also hosts his own YouTube channel discussing DevOps for Developers and is a consultant helping early stage startups getting their applications set up and scaling.He joins the panel to help the Jabber panel understand how to make Node and JavaScript deploy, scale, and grow.PanelAimee KnightAJ O'NealSteve EdwardsGuestWill ButtonSponsorsJavaScript Error and Performance Monitoring | SentryDev Influencers AcceleratorPodcastBootcamp.ioLinksChoice Words about the Upcoming Deprecation of JavaScript DialogsDevOps For Developers - YouTubeDevOps For DevelopersWill ButtonGitHub: Will Button ( rekibnikufesin )Twitter: Will Button ( @wfbutton )PicksAimee- QwiklabsAJ-  Learn Two Languages (and one of them should be Go)AJ- webinstall.devAJ- The Phoenix ProjectAJ- The Vanilla DevOps Git Credentials & Private Packages CheatsheetAJ- Performance - Stack ExchangeAJ- The Zen of PythonAJ- Crockford on JavaScriptWill- Site Reliability EngineeringContact Aimee:Aimee Knight - Software Architect, and International Keynote SpeakerGitHub: Aimee Knight ( AimeeKnight )Twitter: Aimee Knight ( @Aimee_Knight )LinkedIn: Aimee K.aimeemarieknight | InstagramAimee Knight | FacebookContact AJ:AJ ONealCoolAJ86 on GITBeyond Code BootcampBeyond Code Bootcamp | GitHubFollow Beyond Code Bootcamp | FacebookTwitter: Beyond Code Bootcamp ( @_beyondcode )Contact Steve:Twitter: Steve Edwards ( @wonder95 )GitHub: Steve Edwards ( wonder95 )LinkedIn: Steve EdwardsSpecial Guest: Will Button.Sponsored By:Podcast Bootcamp: Launch an Amazing Sounding Podcast in just 4 WEEKS! Work with a 13 year podcasting veteran to get your podcast started off on the right foot! Sentry: Resolve JavaScript errors and performance issues with Sentry

PukiWiki: JSDB(JavaScript for DataBase) Dumped with PukiWiki-Dumper v0.0.14, and uploaded with pukiWikiUploader v0.0.14.

Today I explain how to use routes with mithril.js. I build a simple SPA application with 2 routes and a navbar. You can find the code for this video on my jsfiddle: https://jsfiddle.net/magi16/sd71tqsn/5/ Mithril has really good documentation, and you can read more about routes here: https://mithril.js.org/route.html Mithril js is a light-weight javascript mvc framework, which has similarites to react js. Comment / like / subscribe if this video was helpful to you in any way. Source: https://www.youtube.com/watch?v=cwrsH-V6S3k Uploader: Marcus Gustafsson

Today I explain how to use routes with mithril.js. I build a simple SPA application with 2 routes and a navbar. You can find the code for this video on my jsfiddle: https://jsfiddle.net/magi16/sd71tqsn/5/ Mithril has really good documentation, and you can read more about routes here: https://mithril.js.org/route.html Mithril js is a light-weight javascript mvc framework, which has similarites to react js. Comment / like / subscribe if this video was helpful to you in any way. Source: https://www.youtube.com/watch?v=cwrsH-V6S3k Uploader: Marcus Gustafsson

Josh Mock http://nodevember.org/talk/Josh%20Mock JavaScript fatigue is real. A recent survey showed that 33% of developers feel the JavaScript ecosystem is changing too fast. We regularly make satirical Medium posts and #lolsob tweets about how, as soon as we've gotten comfortable with how a tool works, someone introduces a newer, better, cooler way to do the same thing. To keep up, we could try to be a sponge and spend all our spare time at user groups, reading docs and tutorials, and working through online courses. Or we could be okay with not knowing everything, flex our critical thinking skills, learn about the core software patterns that tend to repeat themselves, and focus on value. Learning to separate the signal from the noise means we can spend less time picking tools and more time solving real problems and mastering the tools we do choose. Let's focus on these skills, so we can put down our work at the end of the day, enjoy our free time and sleep well at night.

Video content can be found here: https://www.youtube.com/channel/UC0BAd8tPlDqFvDYBemHcQPQ/

Source: https://www.youtube.com/watch?v=r4J7Zu1RV40 Uploader: OffensiveCon

Curso completo de Desenvolvimento Web Crie 6 projetosHTML JAVASCRIPT CSS PHP 3. HTML 6. Parágrafos

Curso completo de Desenvolvimento Web Crie 6 projetosHTML JAVASCRIPT CSS PHP 3. HTML 6. Parágrafos

HTML provides a platform-independent way of creating and making multimedia presentations for classroom instruction and making that content available on the Internet. However, time in class is very valuable, so that any way to automate or otherwise assist the presenter in Web page navigation during class can save valuable seconds. This paper describes the use of frames and JavaScript in conjunction with VGA/TV project systems to automate teacher-side Web page navigation for classroom presentations. The methods used are not visually distracting to the students during class, do not require Web server support or an Internet connection (i.e., they can be used with only local hard drive access), and can be used independently of the student-side Web page access so that students who may or may not have browsers that support the features used on the teacher side can still access the content of those pages. (Author/AEF)

Exploiting Music Streaming with JavaScript FRANZ PAYER PROGRAMMER, TACTICAL NETWORK SOLUTIONS As the music industry transitioned from physical to digital distribution, they have forgotten the one thing they hold most dear to them: Their DRM. Many browser-based music streaming services use no DRM to secure their music. By doing this, they leave their library of high quality songs free for the picking. This presentation details the use of JavaScript to circumvent the security of several browser-based music streaming services. By reverse engineering the code for several music players, it is possible to mimic the music player to download songs rather than stream them. Many services that are too difficult or obfuscated to reverse engineer can still be exploited by intercepting streaming traffic and making identical requests to downloads songs. This presentation covers the basics of music streaming, demonstrates browser-based traffic logging to identify and download music files, and describes the use of JavaScript to mimic the legitimate player in order to bypass security. The end result is a Google-Chrome extension which will allow users to download songs as they stream them. Franz Payer (@franz780) is a programmer at Tactical Network Solutions in Columbia, MD. At TNS, Franz develops for several research and development projects, including the company's commercial Reaver Pro software. Franz is a freshman at the University of Maryland, majoring in computer science in the Cybersecurity honors program. Prior to college, Franz led his high school's cybersecurity team, gh0stsec. Cyberexplo.it - http://cyberexplo.it/ Materials: /redirect?q=https%3A%2F%2Fwww.defcon.org%2Fimages%2Fdefcon-21%2Fdc-21-presentations%2FPayer%2FDEFCON-21-Payer-Exploiting-Music-Streaming-with-JavaScript-Updated.pdf&redir_token=vNYus2I253mVCFP3-kUlOBZhdad8MTUzNzQxMzE2MUAxNTM3MzI2NzYx&event=video_description&v=MsIHkOuESE4 /redirect?q=https%3A%2F%2Fwww.defcon.org%2Fimages%2Fdefcon-21%2Fdc-21-presentations%2FPayer%2FExtras-Updated.zip&redir_token=vNYus2I253mVCFP3-kUlOBZhdad8MTUzNzQxMzE2MUAxNTM3MzI2NzYx&event=video_description&v=MsIHkOuESE4 Source: https://www.youtube.com/watch?v=MsIHkOuESE4 Uploader: DEFCONConference

Here are a few javascript files that are necessary for the proper functioning of DreamZoo2. https://dreamzoo2.com

Your data science or machine learning project probably won't just produce a written report. Instead, projects are increasingly expected to produce interactive tools to allow end-users to explore data and results with rich, interactive visualizations. Inevitably, this will be done in a web browser, meaning you'll need to add a quantitatively trained web developer to your team, or have your data scientists spend time learning HTML, Javascript and CSS. Dash, a project by the team that makes Plotly, solves some of these problems by allowing data scientists to build rich and interactive websites in pure python, with minimal knowledge of HTML and absolutely no Javascript. At decisionLab, a London-based data science consultancy producing decision tools, we've embraced Dash to produce proof-of-concept models for our projects in alpha. Although we're not officially connected to the plotly/Dash project, by using the library daily across many projects, we've learned many lessons and what we feel are best practises we'd like to share, and hear feedback on! This talk will give an overview of Dash, how it works and what it can be used for, before outlining some of the common problems that emerge when data scientists are let loose to produce web applications, and web developers have to work with the pydata ecosystem. The talk also covers effective working practises to start producing cool interactive statistical web applications, fast. We'll also identify some of the pitfalls of Dash, and how and when to make the decision to stop using Dash and start building a proper web application. Slides: http://domweldon-europython-2019-dash.s3.eu-west-2.amazonaws.com/index.html Please see our speaker release agreement for details: https://ep2019.europython.eu/events/speaker-release-agreement/

Algorithms and Data Structures implemented in JavaScript for beginners, following best practices. The Algorithms - JavaScript JavaScript Repository of TheAlgorithms, which implements various algorithms and data structures in JavaScript. [![JavaScript Banner][banner]](DIRECTORY.md) [![Checks][checks]][actions] [![Contributions Welcome][welcome]](CONTRIBUTING.md) [![standard.js][standard-logo]][standard-js] [![Discord chat][chat]][discord-server] These implementations are for demonstrative purposes only. Dedicated implementations of these algorithms and data structures are much better for performance and security reasons. We also do not provide any guarantee for api stability. Before contributing to this repository, make sure to read our Contribution Guidelines . You can lookat other TheAlgorithms Repositories or the issues with a "help wanted" label forinspiration regarding what to implement. Our maintainers will guide you through how to make your contribution properlyif you make any mistakes. The names of the maintainers of this repository are listed in the CODEOWNERS file . You can find a list of the algorithms currently in the repository in the directory . Explanations ofmany of the algorithms can be found in the wiki . Thanks to all the contributors ❤️ To restore the repository download the bundle wget https://archive.org/download/github.com-TheAlgorithms-JavaScript_-_2023-10-03_07-37-05/TheAlgorithms-JavaScript_-_2023-10-03_07-37-05.bundle and run: git clone TheAlgorithms-JavaScript_-_2023-10-03_07-37-05.bundle Source: https://github.com/TheAlgorithms/JavaScript Uploader: TheAlgorithms Upload date: 2023-10-03

JavaScript Style Guide Airbnb JavaScript Style Guide() { A mostly reasonable approach to JavaScript Note : this guide assumes you are using Babel , and requires that you use babel-preset-airbnb or the equivalent. It also assumes you are installing shims/polyfills in your app, with airbnb-browser-shims or the equivalent. This guide is available in other languages too. See Translation Other Style Guides ES5 (Deprecated) React CSS-in-JavaScript CSS & Sass Ruby Table of Contents Types References Objects Arrays Destructuring Strings Functions Arrow Functions Classes & Constructors Modules Iterators and Generators Properties Variables Hoisting Comparison Operators & Equality Blocks Control Statements Comments Whitespace Commas Semicolons Type Casting & Coercion Naming Conventions Accessors Events jQuery ECMAScript 5 Compatibility ECMAScript 6+ (ES 2015+) Styles Standard Library Testing Performance Resources In the Wild Translation The JavaScript Style Guide Guide Chat With Us About JavaScript Contributors License Amendments Types - 1.1 Primitives : When you access a primitive type you work directly on its value. - `string`- `number`- `boolean`- `null`- `undefined`- `symbol`- `bigint````javascriptconst foo = 1;let bar = foo;bar = 9;console.log(foo, bar); // =&gt; 1, 9```- Symbols and BigInts cannot be faithfully polyfilled, so they should not be used when targeting browsers/environments that don’t support them natively. - 1.2 Complex : When you access a complex type you work on a reference to its value. - `object`- `array`- `function````javascriptconst foo = [1, 2];const bar = foo;bar[0] = 9;console.log(foo[0], bar[0]); // =&gt; 9, 9``` ⬆ back to top References - 2.1 Use const for all of your references; avoid using var . eslint: &lt;code&gt;prefer-const&lt;/code&gt; , &lt;code&gt;no-const-assign&lt;/code&gt; &gt; Why? This ensures that you can’t reassign your references, which can lead to bugs and difficult to comprehend code.```javascript// badvar a = 1;var b = 2;// goodconst a = 1;const b = 2;``` - 2.2 If you must reassign references, use let instead of var . eslint: &lt;code&gt;no-var&lt;/code&gt; &gt; Why? `let` is block-scoped rather than function-scoped like `var`.```javascript// badvar count = 1;if (true) { count += 1;}// good, use the let.let count = 1;if (true) { count += 1;}``` - 2.3 Note that both let and const are block-scoped, whereas var is function-scoped. ```javascript// const and let only exist in the blocks they are defined in.{ let a = 1; const b = 1; var c = 1;}console.log(a); // ReferenceErrorconsole.log(b); // ReferenceErrorconsole.log(c); // Prints 1```In the above code, you can see that referencing `a` and `b` will produce a ReferenceError, while `c` contains the number. This is because `a` and `b` are block scoped, while `c` is scoped to the containing function. ⬆ back to top Objects - 3.1 Use the literal syntax for object creation. eslint: &lt;code&gt;no-new-object&lt;/code&gt; ```javascript// badconst item = new Object();// goodconst item = {};``` - 3.2 Use computed property names when creating objects with dynamic property names. &gt; Why? They allow you to define all the properties of an object in one place.```javascriptfunction getKey(k) { return `a key named ${k}`;}// badconst obj = { id: 5, name: 'San Francisco',};obj[getKey('enabled')] = true;// goodconst obj = { id: 5, name: 'San Francisco', [getKey('enabled')]: true,};``` - 3.3 Use object method shorthand. eslint: &lt;code&gt;object-shorthand&lt;/code&gt; ```javascript// badconst atom = { value: 1, addValue: function (value) { return atom.value + value; },};// goodconst atom = { value: 1, addValue(value) { return atom.value + value; },};``` - 3.4 Use property value shorthand. eslint: &lt;code&gt;object-shorthand&lt;/code&gt; &gt; Why? It is shorter and descriptive.```javascriptconst lukeSkywalker = 'Luke Skywalker';// badconst obj = { lukeSkywalker: lukeSkywalker,};// goodconst obj = { lukeSkywalker,};``` - 3.5 Group your shorthand properties at the beginning of your object declaration. &gt; Why? It’s easier to tell which properties are using the shorthand.```javascriptconst anakinSkywalker = 'Anakin Skywalker';const lukeSkywalker = 'Luke Skywalker';// badconst obj = { episodeOne: 1, twoJediWalkIntoACantina: 2, lukeSkywalker, episodeThree: 3, mayTheFourth: 4, anakinSkywalker,};// goodconst obj = { lukeSkywalker, anakinSkywalker, episodeOne: 1, twoJediWalkIntoACantina: 2, episodeThree: 3, mayTheFourth: 4,};``` - 3.6 Only quote properties that are invalid identifiers. eslint: &lt;code&gt;quote-props&lt;/code&gt; &gt; Why? In general we consider it subjectively easier to read. It improves syntax highlighting, and is also more easily optimized by many JS engines.```javascript// badconst bad = { 'foo': 3, 'bar': 4, 'data-blah': 5,};// goodconst good = { foo: 3, bar: 4, 'data-blah': 5,};``` - 3.7 Do not call Object.prototype methods directly, such as hasOwnProperty , propertyIsEnumerable , and isPrototypeOf . eslint: &lt;code&gt;no-prototype-builtins&lt;/code&gt; &gt; Why? These methods may be shadowed by properties on the object in question - consider `{ hasOwnProperty: false }` - or, the object may be a null object (`Object.create(null)`).```javascript// badconsole.log(object.hasOwnProperty(key));// goodconsole.log(Object.prototype.hasOwnProperty.call(object, key));// bestconst has = Object.prototype.hasOwnProperty; // cache the lookup once, in module scope.console.log(has.call(object, key));/* or */import has from 'has'; // https://www.npmjs.com/package/hasconsole.log(has(object, key));``` - 3.8 Prefer the object spread syntax over &lt;code&gt;Object.assign&lt;/code&gt; to shallow-copy objects. Use the object rest parameter syntax to get a new object with certain properties omitted. eslint: &lt;code&gt;prefer-object-spread&lt;/code&gt; ```javascript// very badconst original = { a: 1, b: 2 };const copy = Object.assign(original, { c: 3 }); // this mutates `original` ಠ_ಠdelete copy.a; // so does this// badconst original = { a: 1, b: 2 };const copy = Object.assign({}, original, { c: 3 }); // copy =&gt; { a: 1, b: 2, c: 3 }// goodconst original = { a: 1, b: 2 };const copy = { ...original, c: 3 }; // copy =&gt; { a: 1, b: 2, c: 3 }const { a, ...noA } = copy; // noA =&gt; { b: 2, c: 3 }``` ⬆ back to top Arrays - 4.1 Use the literal syntax for array creation. eslint: &lt;code&gt;no-array-constructor&lt;/code&gt; ```javascript// badconst items = new Array();// goodconst items = [];``` - 4.2 Use Array#push instead of direct assignment to add items to an array. ```javascriptconst someStack = [];// badsomeStack[someStack.length] = 'abracadabra';// goodsomeStack.push('abracadabra');``` - 4.3 Use array spreads ... to copy arrays. ```javascript// badconst len = items.length;const itemsCopy = [];let i;for (i = 0; i &lt; len; i += 1) { itemsCopy[i] = items[i];}// goodconst itemsCopy = [...items];``` - 4.4 To convert an iterable object to an array, use spreads ... instead of &lt;code&gt;Array.from&lt;/code&gt; ```javascriptconst foo = document.querySelectorAll('.foo');// goodconst nodes = Array.from(foo);// bestconst nodes = [...foo];``` - 4.5 Use &lt;code&gt;Array.from&lt;/code&gt; for converting an array-like object to an array. ```javascriptconst arrLike = { 0: 'foo', 1: 'bar', 2: 'baz', length: 3 };// badconst arr = Array.prototype.slice.call(arrLike);// goodconst arr = Array.from(arrLike);``` - 4.6 Use &lt;code&gt;Array.from&lt;/code&gt; instead of spread ... for mapping over iterables, because it avoids creating an intermediate array. ```javascript// badconst baz = [...foo].map(bar);// goodconst baz = Array.from(foo, bar);``` - 4.7 Use return statements in array method callbacks. It’s ok to omit the return if the function body consists of a single statement returning an expression without side effects, following 8.2 . eslint: &lt;code&gt;array-callback-return&lt;/code&gt; ```javascript// good[1, 2, 3].map((x) =&gt; { const y = x + 1; return x * y;});// good[1, 2, 3].map((x) =&gt; x + 1);// bad - no returned value means `acc` becomes undefined after the first iteration[[0, 1], [2, 3], [4, 5]].reduce((acc, item, index) =&gt; { const flatten = acc.concat(item);});// good[[0, 1], [2, 3], [4, 5]].reduce((acc, item, index) =&gt; { const flatten = acc.concat(item); return flatten;});// badinbox.filter((msg) =&gt; { const { subject, author } = msg; if (subject === 'Mockingbird') { return author === 'Harper Lee'; } else { return false; }});// goodinbox.filter((msg) =&gt; { const { subject, author } = msg; if (subject === 'Mockingbird') { return author === 'Harper Lee'; } return false;});``` - 4.8 Use line breaks after open and before close array brackets if an array has multiple lines ```javascript// badconst arr = [ [0, 1], [2, 3], [4, 5],];const objectInArray = [{ id: 1,}, { id: 2,}];const numberInArray = [ 1, 2,];// goodconst arr = [[0, 1], [2, 3], [4, 5]];const objectInArray = [ { id: 1, }, { id: 2, },];const numberInArray = [ 1, 2,];``` ⬆ back to top Destructuring - 5.1 Use object destructuring when accessing and using multiple properties of an object. eslint: &lt;code&gt;prefer-destructuring&lt;/code&gt; &gt; Why? Destructuring saves you from creating temporary references for those properties, and from repetitive access of the object. Repeating object access creates more repetitive code, requires more reading, and creates more opportunities for mistakes. Destructuring objects also provides a single site of definition of the object structure that is used in the block, rather than requiring reading the entire block to determine what is used.```javascript// badfunction getFullName(user) { const firstName = user.firstName; const lastName = user.lastName; return `${firstName} ${lastName}`;}// goodfunction getFullName(user) { const { firstName, lastName } = user; return `${firstName} ${lastName}`;}// bestfunction getFullName({ firstName, lastName }) { return `${firstName} ${lastName}`;}``` - 5.2 Use array destructuring. eslint: &lt;code&gt;prefer-destructuring&lt;/code&gt; ```javascriptconst arr = [1, 2, 3, 4];// badconst first = arr[0];const second = arr[1];// goodconst [first, second] = arr;``` - 5.3 Use object destructuring for multiple return values, not array destructuring. &gt; Why? You can add new properties over time or change the order of things without breaking call sites.```javascript// badfunction processInput(input) { // then a miracle occurs return [left, right, top, bottom];}// the caller needs to think about the order of return dataconst [left, __, top] = processInput(input);// goodfunction processInput(input) { // then a miracle occurs return { left, right, top, bottom };}// the caller selects only the data they needconst { left, top } = processInput(input);``` ⬆ back to top Strings - 6.1 Use single quotes '' for strings. eslint: &lt;code&gt;quotes&lt;/code&gt; ```javascript// badconst name = "Capt. Janeway";// bad - template literals should contain interpolation or newlinesconst name = `Capt. Janeway`;// goodconst name = 'Capt. Janeway';``` - 6.2 Strings that cause the line to go over 100 characters should not be written across multiple lines using string concatenation. &gt; Why? Broken strings are painful to work with and make code less searchable.```javascript// badconst errorMessage = 'This is a super long error that was thrown because \of Batman. When you stop to think about how Batman had anything to do \with this, you would get nowhere \fast.';// badconst errorMessage = 'This is a super long error that was thrown because ' + 'of Batman. When you stop to think about how Batman had anything to do ' + 'with this, you would get nowhere fast.';// goodconst errorMessage = 'This is a super long error that was thrown because of Batman. When you stop to think about how Batman had anything to do with this, you would get nowhere fast.';``` - 6.3 When programmatically building up strings, use template strings instead of concatenation. eslint: &lt;code&gt;prefer-template&lt;/code&gt; &lt;code&gt;template-curly-spacing&lt;/code&gt; &gt; Why? Template strings give you a readable, concise syntax with proper newlines and string interpolation features.```javascript// badfunction sayHi(name) { return 'How are you, ' + name + '?';}// badfunction sayHi(name) { return ['How are you, ', name, '?'].join();}// badfunction sayHi(name) { return `How are you, ${ name }?`;}// goodfunction sayHi(name) { return `How are you, ${name}?`;}``` - 6.4 Never use eval() on a string, it opens too many vulnerabilities. eslint: &lt;code&gt;no-eval&lt;/code&gt; - 6.5 Do not unnecessarily escape characters in strings. eslint: &lt;code&gt;no-useless-escape&lt;/code&gt; &gt; Why? Backslashes harm readability, thus they should only be present when necessary.```javascript// badconst foo = '\'this\' \i\s \"quoted\"';// goodconst foo = '\'this\' is "quoted"';const foo = `my name is '${name}'`;``` ⬆ back to top Functions - 7.1 Use named function expressions instead of function declarations. eslint: &lt;code&gt;func-style&lt;/code&gt; &gt; Why? Function declarations are hoisted, which means that it’s easy - too easy - to reference the function before it is defined in the file. This harms readability and maintainability. If you find that a function’s definition is large or complex enough that it is interfering with understanding the rest of the file, then perhaps it’s time to extract it to its own module! Don’t forget to explicitly name the expression, regardless of whether or not the name is inferred from the containing variable (which is often the case in modern browsers or when using compilers such as Babel). This eliminates any assumptions made about the Error’s call stack. ([Discussion](https://github.com/airbnb/javascript/issues/794))```javascript// badfunction foo() { // ...}// badconst foo = function () { // ...};// good// lexical name distinguished from the variable-referenced invocation(s)const short = function longUniqueMoreDescriptiveLexicalFoo() { // ...};``` - 7.2 Wrap immediately invoked function expressions in parentheses. eslint: &lt;code&gt;wrap-iife&lt;/code&gt; &gt; Why? An immediately invoked function expression is a single unit - wrapping both it, and its invocation parens, in parens, cleanly expresses this. Note that in a world with modules everywhere, you almost never need an IIFE.```javascript// immediately-invoked function expression (IIFE)(function () { console.log('Welcome to the Internet. Please follow me.');}());``` - 7.3 Never declare a function in a non-function block ( if , while , etc). Assign the function to a variable instead. Browsers will allow you to do it, but they all interpret it differently, which is bad news bears. eslint: &lt;code&gt;no-loop-func&lt;/code&gt; - 7.4 Note: ECMA-262 defines a block as a list of statements. A function declaration is not a statement. ```javascript// badif (currentUser) { function test() { console.log('Nope.'); }}// goodlet test;if (currentUser) { test = () =&gt; { console.log('Yup.'); };}``` - 7.5 Never name a parameter arguments . This will take precedence over the arguments object that is given to every function scope. ```javascript// badfunction foo(name, options, arguments) { // ...}// goodfunction foo(name, options, args) { // ...}``` - 7.6 Never use arguments , opt to use rest syntax ... instead. eslint: &lt;code&gt;prefer-rest-params&lt;/code&gt; &gt; Why? `...` is explicit about which arguments you want pulled. Plus, rest arguments are a real Array, and not merely Array-like like `arguments`.```javascript// badfunction concatenateAll() { const args = Array.prototype.slice.call(arguments); return args.join('');}// goodfunction concatenateAll(...args) { return args.join('');}``` - 7.7 Use default parameter syntax rather than mutating function arguments. ```javascript// really badfunction handleThings(opts) { // No! We shouldn’t mutate function arguments. // Double bad: if opts is falsy it'll be set to an object which may // be what you want but it can introduce subtle bugs. opts = opts || {}; // ...}// still badfunction handleThings(opts) { if (opts === void 0) { opts = {}; } // ...}// goodfunction handleThings(opts = {}) { // ...}``` - 7.8 Avoid side effects with default parameters. &gt; Why? They are confusing to reason about.```javascriptvar b = 1;// badfunction count(a = b++) { console.log(a);}count(); // 1count(); // 2count(3); // 3count(); // 3``` - 7.9 Always put default parameters last. eslint: &lt;code&gt;default-param-last&lt;/code&gt; ```javascript// badfunction handleThings(opts = {}, name) { // ...}// goodfunction handleThings(name, opts = {}) { // ...}``` - 7.10 Never use the Function constructor to create a new function. eslint: &lt;code&gt;no-new-func&lt;/code&gt; &gt; Why? Creating a function in this way evaluates a string similarly to `eval()`, which opens vulnerabilities.```javascript// badvar add = new Function('a', 'b', 'return a + b');// still badvar subtract = Function('a', 'b', 'return a - b');``` - 7.11 Spacing in a function signature. eslint: &lt;code&gt;space-before-function-paren&lt;/code&gt; &lt;code&gt;space-before-blocks&lt;/code&gt; &gt; Why? Consistency is good, and you shouldn’t have to add or remove a space when adding or removing a name.```javascript// badconst f = function(){};const g = function (){};const h = function() {};// goodconst x = function () {};const y = function a() {};``` - 7.12 Never mutate parameters. eslint: &lt;code&gt;no-param-reassign&lt;/code&gt; &gt; Why? Manipulating objects passed in as parameters can cause unwanted variable side effects in the original caller.```javascript// badfunction f1(obj) { obj.key = 1;}// goodfunction f2(obj) { const key = Object.prototype.hasOwnProperty.call(obj, 'key') ? obj.key : 1;}``` - 7.13 Never reassign parameters. eslint: &lt;code&gt;no-param-reassign&lt;/code&gt; &gt; Why? Reassigning parameters can lead to unexpected behavior, especially when accessing the `arguments` object. It can also cause optimization issues, especially in V8.```javascript// badfunction f1(a) { a = 1; // ...}function f2(a) { if (!a) { a = 1; } // ...}// goodfunction f3(a) { const b = a || 1; // ...}function f4(a = 1) { // ...}``` - 7.14 Prefer the use of the spread syntax ... to call variadic functions. eslint: &lt;code&gt;prefer-spread&lt;/code&gt; &gt; Why? It’s cleaner, you don’t need to supply a context, and you can not easily compose `new` with `apply`.```javascript// badconst x = [1, 2, 3, 4, 5];console.log.apply(console, x);// goodconst x = [1, 2, 3, 4, 5];console.log(...x);// badnew (Function.prototype.bind.apply(Date, [null, 2016, 8, 5]));// goodnew Date(...[2016, 8, 5]);``` - 7.15 Functions with multiline signatures, or invocations, should be indented just like every other multiline list in this guide: with each item on a line by itself, with a trailing comma on the last item. eslint: &lt;code&gt;function-paren-newline&lt;/code&gt; ```javascript// badfunction foo(bar, baz, quux) { // ...}// goodfunction foo( bar, baz, quux,) { // ...}// badconsole.log(foo, bar, baz);// goodconsole.log( foo, bar, baz,);``` ⬆ back to top Arrow Functions - 8.1 When you must use an anonymous function (as when passing an inline callback), use arrow function notation. eslint: &lt;code&gt;prefer-arrow-callback&lt;/code&gt; , &lt;code&gt;arrow-spacing&lt;/code&gt; &gt; Why? It creates a version of the function that executes in the context of `this`, which is usually what you want, and is a more concise syntax.&gt; Why not? If you have a fairly complicated function, you might move that logic out into its own named function expression.```javascript// bad[1, 2, 3].map(function (x) { const y = x + 1; return x * y;});// good[1, 2, 3].map((x) =&gt; { const y = x + 1; return x * y;});``` - 8.2 If the function body consists of a single statement returning an expression without side effects, omit the braces and use the implicit return. Otherwise, keep the braces and use a return statement. eslint: &lt;code&gt;arrow-parens&lt;/code&gt; , &lt;code&gt;arrow-body-style&lt;/code&gt; &gt; Why? Syntactic sugar. It reads well when multiple functions are chained together.```javascript// bad[1, 2, 3].map((number) =&gt; { const nextNumber = number + 1; `A string containing the ${nextNumber}.`;});// good[1, 2, 3].map((number) =&gt; `A string containing the ${number + 1}.`);// good[1, 2, 3].map((number) =&gt; { const nextNumber = number + 1; return `A string containing the ${nextNumber}.`;});// good[1, 2, 3].map((number, index) =&gt; ({ [index]: number,}));// No implicit return with side effectsfunction foo(callback) { const val = callback(); if (val === true) { // Do something if callback returns true }}let bool = false;// badfoo(() =&gt; bool = true);// goodfoo(() =&gt; { bool = true;});``` - 8.3 In case the expression spans over multiple lines, wrap it in parentheses for better readability. &gt; Why? It shows clearly where the function starts and ends.```javascript// bad['get', 'post', 'put'].map((httpMethod) =&gt; Object.prototype.hasOwnProperty.call( httpMagicObjectWithAVeryLongName, httpMethod, ));// good['get', 'post', 'put'].map((httpMethod) =&gt; ( Object.prototype.hasOwnProperty.call( httpMagicObjectWithAVeryLongName, httpMethod, )));``` - 8.4 Always include parentheses around arguments for clarity and consistency. eslint: &lt;code&gt;arrow-parens&lt;/code&gt; &gt; Why? Minimizes diff churn when adding or removing arguments.```javascript// bad[1, 2, 3].map(x =&gt; x * x);// good[1, 2, 3].map((x) =&gt; x * x);// bad[1, 2, 3].map(number =&gt; ( `A long string with the ${number}. It’s so long that we don’t want it to take up space on the .map line!`));// good[1, 2, 3].map((number) =&gt; ( `A long string with the ${number}. It’s so long that we don’t want it to take up space on the .map line!`));// bad[1, 2, 3].map(x =&gt; { const y = x + 1; return x * y;});// good[1, 2, 3].map((x) =&gt; { const y = x + 1; return x * y;});``` - 8.5 Avoid confusing arrow function syntax ( =&gt; ) with comparison operators ( &lt;= , &gt;= ). eslint: &lt;code&gt;no-confusing-arrow&lt;/code&gt; ```javascript// badconst itemHeight = (item) =&gt; item.height &lt;= 256 ? item.largeSize : item.smallSize;// badconst itemHeight = (item) =&gt; item.height &gt;= 256 ? item.largeSize : item.smallSize;// goodconst itemHeight = (item) =&gt; (item.height &lt;= 256 ? item.largeSize : item.smallSize);// goodconst itemHeight = (item) =&gt; { const { height, largeSize, smallSize } = item; return height &lt;= 256 ? largeSize : smallSize;};``` - 8.6 Enforce the location of arrow function bodies with implicit returns. eslint: &lt;code&gt;implicit-arrow-linebreak&lt;/code&gt; ```javascript// bad(foo) =&gt; bar;(foo) =&gt; (bar);// good(foo) =&gt; bar;(foo) =&gt; (bar);(foo) =&gt; ( bar)``` ⬆ back to top Classes & Constructors - 9.1 Always use class . Avoid manipulating prototype directly. &gt; Why? `class` syntax is more concise and easier to reason about.```javascript// badfunction Queue(contents = []) { this.queue = [...contents];}Queue.prototype.pop = function () { const value = this.queue[0]; this.queue.splice(0, 1); return value;};// goodclass Queue { constructor(contents = []) { this.queue = [...contents]; } pop() { const value = this.queue[0]; this.queue.splice(0, 1); return value; }}``` - 9.2 Use extends for inheritance. &gt; Why? It is a built-in way to inherit prototype functionality without breaking `instanceof`.```javascript// badconst inherits = require('inherits');function PeekableQueue(contents) { Queue.apply(this, contents);}inherits(PeekableQueue, Queue);PeekableQueue.prototype.peek = function () { return this.queue[0];};// goodclass PeekableQueue extends Queue { peek() { return this.queue[0]; }}``` - 9.3 Methods can return this to help with method chaining. ```javascript// badJedi.prototype.jump = function () { this.jumping = true; return true;};Jedi.prototype.setHeight = function (height) { this.height = height;};const luke = new Jedi();luke.jump(); // =&gt; trueluke.setHeight(20); // =&gt; undefined// goodclass Jedi { jump() { this.jumping = true; return this; } setHeight(height) { this.height = height; return this; }}const luke = new Jedi();luke.jump() .setHeight(20);``` - 9.4 It’s okay to write a custom toString() method, just make sure it works successfully and causes no side effects. ```javascriptclass Jedi { constructor(options = {}) { this.name = options.name || 'no name'; } getName() { return this.name; } toString() { return `Jedi - ${this.getName()}`; }}``` - 9.5 Classes have a default constructor if one is not specified. An empty constructor function or one that just delegates to a parent class is unnecessary. eslint: &lt;code&gt;no-useless-constructor&lt;/code&gt; ```javascript// badclass Jedi { constructor() {} getName() { return this.name; }}// badclass Rey extends Jedi { constructor(...args) { super(...args); }}// goodclass Rey extends Jedi { constructor(...args) { super(...args); this.name = 'Rey'; }}``` - 9.6 Avoid duplicate class members. eslint: &lt;code&gt;no-dupe-class-members&lt;/code&gt; &gt; Why? Duplicate class member declarations will silently prefer the last one - having duplicates is almost certainly a bug.```javascript// badclass Foo { bar() { return 1; } bar() { return 2; }}// goodclass Foo { bar() { return 1; }}// goodclass Foo { bar() { return 2; }}``` - 9.7 Class methods should use this or be made into a static method unless an external library or framework requires using specific non-static methods. Being an instance method should indicate that it behaves differently based on properties of the receiver. eslint: &lt;code&gt;class-methods-use-this&lt;/code&gt; ```javascript// badclass Foo { bar() { console.log('bar'); }}// good - this is usedclass Foo { bar() { console.log(this.bar); }}// good - constructor is exemptclass Foo { constructor() { // ... }}// good - static methods aren't expected to use thisclass Foo { static bar() { console.log('bar'); }}``` ⬆ back to top Modules - 10.1 Always use modules ( import / export ) over a non-standard module system. You can always transpile to your preferred module system. &gt; Why? Modules are the future, let’s start using the future now.```javascript// badconst AirbnbStyleGuide = require('./AirbnbStyleGuide');module.exports = AirbnbStyleGuide.es6;// okimport AirbnbStyleGuide from './AirbnbStyleGuide';export default AirbnbStyleGuide.es6;// bestimport { es6 } from './AirbnbStyleGuide';export default es6;``` - 10.2 Do not use wildcard imports. &gt; Why? This makes sure you have a single default export.```javascript// badimport * as AirbnbStyleGuide from './AirbnbStyleGuide';// goodimport AirbnbStyleGuide from './AirbnbStyleGuide';``` - 10.3 And do not export directly from an import. &gt; Why? Although the one-liner is concise, having one clear way to import and one clear way to export makes things consistent.```javascript// bad// filename es6.jsexport { es6 as default } from './AirbnbStyleGuide';// good// filename es6.jsimport { es6 } from './AirbnbStyleGuide';export default es6;``` - 10.4 Only import from a path in one place. eslint: &lt;code&gt;no-duplicate-imports&lt;/code&gt; Why? Having multiple lines that import from the same path can make code harder to maintain. ```javascript// badimport foo from 'foo';// … some other imports … //import { named1, named2 } from 'foo';// goodimport foo, { named1, named2 } from 'foo';// goodimport foo, { named1, named2,} from 'foo';``` - 10.5 Do not export mutable bindings. eslint: &lt;code&gt;import/no-mutable-exports&lt;/code&gt; Why? Mutation should be avoided in general, but in particular when exporting mutable bindings. While this technique may be needed for some special cases, in general, only constant references should be exported. ```javascript// badlet foo = 3;export { foo };// goodconst foo = 3;export { foo };``` - 10.6 In modules with a single export, prefer default export over named export. eslint: &lt;code&gt;import/prefer-default-export&lt;/code&gt; Why? To encourage more files that only ever export one thing, which is better for readability and maintainability. ```javascript// badexport function foo() {}// goodexport default function foo() {}``` - 10.7 Put all import s above non-import statements. eslint: &lt;code&gt;import/first&lt;/code&gt; Why? Since import s are hoisted, keeping them all at the top prevents surprising behavior. ```javascript// badimport foo from 'foo';foo.init();import bar from 'bar';// goodimport foo from 'foo';import bar from 'bar';foo.init();``` - 10.8 Multiline imports should be indented just like multiline array and object literals. eslint: &lt;code&gt;object-curly-newline&lt;/code&gt; &gt; Why? The curly braces follow the same indentation rules as every other curly brace block in the style guide, as do the trailing commas.```javascript// badimport {longNameA, longNameB, longNameC, longNameD, longNameE} from 'path';// goodimport { longNameA, longNameB, longNameC, longNameD, longNameE,} from 'path';``` - 10.9 Disallow Webpack loader syntax in module import statements. eslint: &lt;code&gt;import/no-webpack-loader-syntax&lt;/code&gt; Why? Since using Webpack syntax in the imports couples the code to a module bundler. Prefer using the loader syntax in webpack.config.js . ```javascript// badimport fooSass from 'css!sass!foo.scss';import barCss from 'style!css!bar.css';// goodimport fooSass from 'foo.scss';import barCss from 'bar.css';``` - 10.10 Do not include JavaScript filename extensions eslint: &lt;code&gt;import/extensions&lt;/code&gt; Why? Including extensions inhibits refactoring, and inappropriately hardcodes implementation details of the module you're importing in every consumer. ```javascript// badimport foo from './foo.js';import bar from './bar.jsx';import baz from './baz/index.jsx';// goodimport foo from './foo';import bar from './bar';import baz from './baz';``` ⬆ back to top Iterators and Generators - 11.1 Don’t use iterators. Prefer JavaScript’s higher-order functions instead of loops like for-in or for-of . eslint: &lt;code&gt;no-iterator&lt;/code&gt; &lt;code&gt;no-restricted-syntax&lt;/code&gt; &gt; Why? This enforces our immutable rule. Dealing with pure functions that return values is easier to reason about than side effects.&gt; Use `map()` / `every()` / `filter()` / `find()` / `findIndex()` / `reduce()` / `some()` / ... to iterate over arrays, and `Object.keys()` / `Object.values()` / `Object.entries()` to produce arrays so you can iterate over objects.```javascriptconst numbers = [1, 2, 3, 4, 5];// badlet sum = 0;for (let num of numbers) { sum += num;}sum === 15;// goodlet sum = 0;numbers.forEach((num) =&gt; { sum += num;});sum === 15;// best (use the functional force)const sum = numbers.reduce((total, num) =&gt; total + num, 0);sum === 15;// badconst increasedByOne = [];for (let i = 0; i &lt; numbers.length; i++) { increasedByOne.push(numbers[i] + 1);}// goodconst increasedByOne = [];numbers.forEach((num) =&gt; { increasedByOne.push(num + 1);});// best (keeping it functional)const increasedByOne = numbers.map((num) =&gt; num + 1);``` - 11.2 Don’t use generators for now. &gt; Why? They don’t transpile well to ES5. - 11.3 If you must use generators, or if you disregard our advice , make sure their function signature is spaced properly. eslint: &lt;code&gt;generator-star-spacing&lt;/code&gt; &gt; Why? `function` and `*` are part of the same conceptual keyword - `*` is not a modifier for `function`, `function*` is a unique construct, different from `function`.```javascript// badfunction * foo() { // ...}// badconst bar = function * () { // ...};// badconst baz = function *() { // ...};// badconst quux = function*() { // ...};// badfunction*foo() { // ...}// badfunction *foo() { // ...}// very badfunction*foo() { // ...}// very badconst wat = function*() { // ...};// goodfunction* foo() { // ...}// goodconst foo = function* () { // ...};``` ⬆ back to top Properties - 12.1 Use dot notation when accessing properties. eslint: &lt;code&gt;dot-notation&lt;/code&gt; ```javascriptconst luke = { jedi: true, age: 28,};// badconst isJedi = luke['jedi'];// goodconst isJedi = luke.jedi;``` - 12.2 Use bracket notation [] when accessing properties with a variable. ```javascriptconst luke = { jedi: true, age: 28,};function getProp(prop) { return luke[prop];}const isJedi = getProp('jedi');``` - 12.3 Use exponentiation operator ** when calculating exponentiations. eslint: &lt;code&gt;no-restricted-properties&lt;/code&gt; . ```javascript// badconst binary = Math.pow(2, 10);// goodconst binary = 2 ** 10;``` ⬆ back to top Variables - 13.1 Always use const or let to declare variables. Not doing so will result in global variables. We want to avoid polluting the global namespace. Captain Planet warned us of that. eslint: &lt;code&gt;no-undef&lt;/code&gt; &lt;code&gt;prefer-const&lt;/code&gt; ```javascript// badsuperPower = new SuperPower();// goodconst superPower = new SuperPower();``` - 13.2 Use one const or let declaration per variable or assignment. eslint: &lt;code&gt;one-var&lt;/code&gt; &gt; Why? It’s easier to add new variable declarations this way, and you never have to worry about swapping out a `;` for a `,` or introducing punctuation-only diffs. You can also step through each declaration with the debugger, instead of jumping through all of them at once.```javascript// badconst items = getItems(), goSportsTeam = true, dragonball = 'z';// bad// (compare to above, and try to spot the mistake)const items = getItems(), goSportsTeam = true; dragonball = 'z';// goodconst items = getItems();const goSportsTeam = true;const dragonball = 'z';``` - 13.3 Group all your const s and then group all your let s. &gt; Why? This is helpful when later on you might need to assign a variable depending on one of the previously assigned variables.```javascript// badlet i, len, dragonball, items = getItems(), goSportsTeam = true;// badlet i;const items = getItems();let dragonball;const goSportsTeam = true;let len;// goodconst goSportsTeam = true;const items = getItems();let dragonball;let i;let length;``` - 13.4 Assign variables where you need them, but place them in a reasonable place. &gt; Why? `let` and `const` are block scoped and not function scoped.```javascript// bad - unnecessary function callfunction checkName(hasName) { const name = getName(); if (hasName === 'test') { return false; } if (name === 'test') { this.setName(''); return false; } return name;}// goodfunction checkName(hasName) { if (hasName === 'test') { return false; } const name = getName(); if (name === 'test') { this.setName(''); return false; } return name;}``` - 13.5 Don’t chain variable assignments. eslint: &lt;code&gt;no-multi-assign&lt;/code&gt; &gt; Why? Chaining variable assignments creates implicit global variables.```javascript// bad(function example() { // JavaScript interprets this as // let a = ( b = ( c = 1 ) ); // The let keyword only applies to variable a; variables b and c become // global variables. let a = b = c = 1;}());console.log(a); // throws ReferenceErrorconsole.log(b); // 1console.log(c); // 1// good(function example() { let a = 1; let b = a; let c = a;}());console.log(a); // throws ReferenceErrorconsole.log(b); // throws ReferenceErrorconsole.log(c); // throws ReferenceError// the same applies for `const```` - 13.6 Avoid using unary increments and decrements ( ++ , -- ). eslint &lt;code&gt;no-plusplus&lt;/code&gt; &gt; Why? Per the eslint documentation, unary increment and decrement statements are subject to automatic semicolon insertion and can cause silent errors with incrementing or decrementing values within an application. It is also more expressive to mutate your values with statements like `num += 1` instead of `num++` or `num ++`. Disallowing unary increment and decrement statements also prevents you from pre-incrementing/pre-decrementing values unintentionally which can also cause unexpected behavior in your programs.```javascript// badconst array = [1, 2, 3];let num = 1;num++;--num;let sum = 0;let truthyCount = 0;for (let i = 0; i &lt; array.length; i++) { let value = array[i]; sum += value; if (value) { truthyCount++; }}// goodconst array = [1, 2, 3];let num = 1;num += 1;num -= 1;const sum = array.reduce((a, b) =&gt; a + b, 0);const truthyCount = array.filter(Boolean).length;``` - 13.7 Avoid linebreaks before or after = in an assignment. If your assignment violates &lt;code&gt;max-len&lt;/code&gt; , surround the value in parens. eslint &lt;code&gt;operator-linebreak&lt;/code&gt; . &gt; Why? Linebreaks surrounding `=` can obfuscate the value of an assignment.```javascript// badconst foo = superLongLongLongLongLongLongLongLongFunctionName();// badconst foo = 'superLongLongLongLongLongLongLongLongString';// goodconst foo = ( superLongLongLongLongLongLongLongLongFunctionName());// goodconst foo = 'superLongLongLongLongLongLongLongLongString';``` - 13.8 Disallow unused variables. eslint: &lt;code&gt;no-unused-vars&lt;/code&gt; &gt; Why? Variables that are declared and not used anywhere in the code are most likely an error due to incomplete refactoring. Such variables take up space in the code and can lead to confusion by readers.```javascript// badvar some_unused_var = 42;// Write-only variables are not considered as used.var y = 10;y = 5;// A read for a modification of itself is not considered as used.var z = 0;z = z + 1;// Unused function arguments.function getX(x, y) { return x;}// goodfunction getXPlusY(x, y) { return x + y;}var x = 1;var y = a + 2;alert(getXPlusY(x, y));// 'type' is ignored even if unused because it has a rest property sibling.// This is a form of extracting an object that omits the specified keys.var { type, ...coords } = data;// 'coords' is now the 'data' object without its 'type' property.``` ⬆ back to top Hoisting - 14.1 var declarations get hoisted to the top of their closest enclosing function scope, their assignment does not. const and let declarations are blessed with a new concept called Temporal Dead Zones (TDZ) . It’s important to know why typeof is no longer safe . ```javascript// we know this wouldn’t work (assuming there// is no notDefined global variable)function example() { console.log(notDefined); // =&gt; throws a ReferenceError}// creating a variable declaration after you// reference the variable will work due to// variable hoisting. Note: the assignment// value of `true` is not hoisted.function example() { console.log(declaredButNotAssigned); // =&gt; undefined var declaredButNotAssigned = true;}// the interpreter is hoisting the variable// declaration to the top of the scope,// which means our example could be rewritten as:function example() { let declaredButNotAssigned; console.log(declaredButNotAssigned); // =&gt; undefined declaredButNotAssigned = true;}// using const and letfunction example() { console.log(declaredButNotAssigned); // =&gt; throws a ReferenceError console.log(typeof declaredButNotAssigned); // =&gt; throws a ReferenceError const declaredButNotAssigned = true;}``` - 14.2 Anonymous function expressions hoist their variable name, but not the function assignment. ```javascriptfunction example() { console.log(anonymous); // =&gt; undefined anonymous(); // =&gt; TypeError anonymous is not a function var anonymous = function () { console.log('anonymous function expression'); };}``` - 14.3 Named function expressions hoist the variable name, not the function name or the function body. ```javascriptfunction example() { console.log(named); // =&gt; undefined named(); // =&gt; TypeError named is not a function superPower(); // =&gt; ReferenceError superPower is not defined var named = function superPower() { console.log('Flying'); };}// the same is true when the function name// is the same as the variable name.function example() { console.log(named); // =&gt; undefined named(); // =&gt; TypeError named is not a function var named = function named() { console.log('named'); };}``` - 14.4 Function declarations hoist their name and the function body. ```javascriptfunction example() { superPower(); // =&gt; Flying function superPower() { console.log('Flying'); }}``` For more information refer to JavaScript Scoping & Hoisting by Ben Cherry . ⬆ back to top Comparison Operators & Equality - 15.1 Use === and !== over == and != . eslint: &lt;code&gt;eqeqeq&lt;/code&gt; - 15.2 Conditional statements such as the if statement evaluate their expression using coercion with the ToBoolean abstract method and always follow these simple rules: - **Objects** evaluate to **true**- **Undefined** evaluates to **false**- **Null** evaluates to **false**- **Booleans** evaluate to **the value of the boolean**- **Numbers** evaluate to **false** if **+0, -0, or NaN**, otherwise **true**- **Strings** evaluate to **false** if an empty string `''`, otherwise **true**```javascriptif ([0] && []) { // true // an array (even an empty one) is an object, objects will evaluate to true}``` - 15.3 Use shortcuts for booleans, but explicit comparisons for strings and numbers. ```javascript// badif (isValid === true) { // ...}// goodif (isValid) { // ...}// badif (name) { // ...}// goodif (name !== '') { // ...}// badif (collection.length) { // ...}// goodif (collection.length &gt; 0) { // ...}``` - 15.4 For more information see Truth Equality and JavaScript by Angus Croll. - 15.5 Use braces to create blocks in case and default clauses that contain lexical declarations (e.g. let , const , function , and class ). eslint: &lt;code&gt;no-case-declarations&lt;/code&gt; &gt; Why? Lexical declarations are visible in the entire `switch` block but only get initialized when assigned, which only happens when its `case` is reached. This causes problems when multiple `case` clauses attempt to define the same thing.```javascript// badswitch (foo) { case 1: let x = 1; break; case 2: const y = 2; break; case 3: function f() { // ... } break; default: class C {}}// goodswitch (foo) { case 1: { let x = 1; break; } case 2: { const y = 2; break; } case 3: { function f() { // ... } break; } case 4: bar(); break; default: { class C {} }}``` - 15.6 Ternaries should not be nested and generally be single line expressions. eslint: &lt;code&gt;no-nested-ternary&lt;/code&gt; ```javascript// badconst foo = maybe1 &gt; maybe2 ? "bar" : value1 &gt; value2 ? "baz" : null;// split into 2 separated ternary expressionsconst maybeNull = value1 &gt; value2 ? 'baz' : null;// betterconst foo = maybe1 &gt; maybe2 ? 'bar' : maybeNull;// bestconst foo = maybe1 &gt; maybe2 ? 'bar' : maybeNull;``` - 15.7 Avoid unneeded ternary statements. eslint: &lt;code&gt;no-unneeded-ternary&lt;/code&gt; ```javascript// badconst foo = a ? a : b;const bar = c ? true : false;const baz = c ? false : true;// goodconst foo = a || b;const bar = !!c;const baz = !c;``` - 15.8 When mixing operators, enclose them in parentheses. The only exception is the standard arithmetic operators: + , - , and ** since their precedence is broadly understood. We recommend enclosing / and * in parentheses because their precedence can be ambiguous when they are mixed. eslint: &lt;code&gt;no-mixed-operators&lt;/code&gt; &gt; Why? This improves readability and clarifies the developer’s intention.```javascript// badconst foo = a && b &lt; 0 || c &gt; 0 || d + 1 === 0;// badconst bar = a ** b - 5 % d;// bad// one may be confused into thinking (a || b) && cif (a || b && c) { return d;}// badconst bar = a + b / c * d;// goodconst foo = (a && b &lt; 0) || c &gt; 0 || (d + 1 === 0);// goodconst bar = a ** b - (5 % d);// goodif (a || (b && c)) { return d;}// goodconst bar = a + (b / c) * d;``` ⬆ back to top Blocks - 16.1 Use braces with all multiline blocks. eslint: &lt;code&gt;nonblock-statement-body-position&lt;/code&gt; ```javascript// badif (test) return false;// goodif (test) return false;// goodif (test) { return false;}// badfunction foo() { return false; }// goodfunction bar() { return false;}``` - 16.2 If you’re using multiline blocks with if and else , put else on the same line as your if block’s closing brace. eslint: &lt;code&gt;brace-style&lt;/code&gt; ```javascript// badif (test) { thing1(); thing2();}else { thing3();}// goodif (test) { thing1(); thing2();} else { thing3();}``` - 16.3 If an if block always executes a return statement, the subsequent else block is unnecessary. A return in an else if block following an if block that contains a return can be separated into multiple if blocks. eslint: &lt;code&gt;no-else-return&lt;/code&gt; ```javascript// badfunction foo() { if (x) { return x; } else { return y; }}// badfunction cats() { if (x) { return x; } else if (y) { return y; }}// badfunction dogs() { if (x) { return x; } else { if (y) { return y; } }}// goodfunction foo() { if (x) { return x; } return y;}// goodfunction cats() { if (x) { return x; } if (y) { return y; }}// goodfunction dogs(x) { if (x) { if (z) { return y; } } else { return z; }}``` ⬆ back to top Control Statements - 17.1 In case your control statement ( if , while etc.) gets too long or exceeds the maximum line length, each (grouped) condition could be put into a new line. The logical operator should begin the line. &gt; Why? Requiring operators at the beginning of the line keeps the operators aligned and follows a pattern similar to method chaining. This also improves readability by making it easier to visually follow complex logic.```javascript// badif ((foo === 123 || bar === 'abc') && doesItLookGoodWhenItBecomesThatLong() && isThisReallyHappening()) { thing1();}// badif (foo === 123 && bar === 'abc') { thing1();}// badif (foo === 123 && bar === 'abc') { thing1();}// badif ( foo === 123 && bar === 'abc') { thing1();}// goodif ( foo === 123 && bar === 'abc') { thing1();}// goodif ( (foo === 123 || bar === 'abc') && doesItLookGoodWhenItBecomesThatLong() && isThisReallyHappening()) { thing1();}// goodif (foo === 123 && bar === 'abc') { thing1();}``` - 17.2 Don't use selection operators in place of control statements. ```javascript// bad!isRunning && startRunning();// goodif (!isRunning) { startRunning();}``` ⬆ back to top Comments - 18.1 Use /** ... */ for multiline comments. ```javascript// bad// make() returns a new element// based on the passed in tag name//// @param {String} tag// @return {Element} elementfunction make(tag) { // ... return element;}// good/** * make() returns a new element * based on the passed-in tag name */function make(tag) { // ... return element;}``` - 18.2 Use // for single line comments. Place single line comments on a newline above the subject of the comment. Put an empty line before the comment unless it’s on the first line of a block. ```javascript// badconst active = true; // is current tab// good// is current tabconst active = true;// badfunction getType() { console.log('fetching type...'); // set the default type to 'no type' const type = this.type || 'no type'; return type;}// goodfunction getType() { console.log('fetching type...'); // set the default type to 'no type' const type = this.type || 'no type'; return type;}// also goodfunction getType() { // set the default type to 'no type' const type = this.type || 'no type'; return type;}``` - 18.3 Start all comments with a space to make it easier to read. eslint: &lt;code&gt;spaced-comment&lt;/code&gt; ```javascript// bad//is current tabconst active = true;// good// is current tabconst active = true;// bad/** *make() returns a new element *based on the passed-in tag name */function make(tag) { // ... return element;}// good/** * make() returns a new element * based on the passed-in tag name */function make(tag) { // ... return element;}``` - 18.4 Prefixing your comments with FIXME or TODO helps other developers quickly understand if you’re pointing out a problem that needs to be revisited, or if you’re suggesting a solution to the problem that needs to be implemented. These are different than regular comments because they are actionable. The actions are FIXME: -- need to figure this out or TODO: -- need to implement . - 18.5 Use // FIXME: to annotate problems. ```javascriptclass Calculator extends Abacus { constructor() { super(); // FIXME: shouldn’t use a global here total = 0; }}``` - 18.6 Use // TODO: to annotate solutions to problems. ```javascriptclass Calculator extends Abacus { constructor() { super(); // TODO: total should be configurable by an options param this.total = 0; }}``` ⬆ back to top Whitespace - 19.1 Use soft tabs (space character) set to 2 spaces. eslint: &lt;code&gt;indent&lt;/code&gt; ```javascript// badfunction foo() {∙∙∙∙let name;}// badfunction bar() {∙let name;}// goodfunction baz() {∙∙let name;}``` - 19.2 Place 1 space before the leading brace. eslint: &lt;code&gt;space-before-blocks&lt;/code&gt; ```javascript// badfunction test(){ console.log('test');}// goodfunction test() { console.log('test');}// baddog.set('attr',{ age: '1 year', breed: 'Bernese Mountain Dog',});// gooddog.set('attr', { age: '1 year', breed: 'Bernese Mountain Dog',});``` - 19.3 Place 1 space before the opening parenthesis in control statements ( if , while etc.). Place no space between the argument list and the function name in function calls and declarations. eslint: &lt;code&gt;keyword-spacing&lt;/code&gt; ```javascript// badif(isJedi) { fight ();}// goodif (isJedi) { fight();}// badfunction fight () { console.log ('Swooosh!');}// goodfunction fight() { console.log('Swooosh!');}``` - 19.4 Set off operators with spaces. eslint: &lt;code&gt;space-infix-ops&lt;/code&gt; ```javascript// badconst x=y+5;// goodconst x = y + 5;``` - 19.5 End files with a single newline character. eslint: &lt;code&gt;eol-last&lt;/code&gt; ```javascript// badimport { es6 } from './AirbnbStyleGuide'; // ...export default es6;``````javascript// badimport { es6 } from './AirbnbStyleGuide'; // ...export default es6;↵↵``````javascript// goodimport { es6 } from './AirbnbStyleGuide'; // ...export default es6;↵``` - 19.6 Use indentation when making long method chains (more than 2 method chains). Use a leading dot, which emphasizes that the line is a method call, not a new statement. eslint: &lt;code&gt;newline-per-chained-call&lt;/code&gt; &lt;code&gt;no-whitespace-before-property&lt;/code&gt; ```javascript// bad$('#items').find('.selected').highlight().end().find('.open').updateCount();// bad$('#items'). find('.selected'). highlight(). end(). find('.open'). updateCount();// good$('#items') .find('.selected') .highlight() .end() .find('.open') .updateCount();// badconst leds = stage.selectAll('.led').data(data).enter().append('svg:svg').classed('led', true) .attr('width', (radius + margin) * 2).append('svg:g') .attr('transform', `translate(${radius + margin},${radius + margin})`) .call(tron.led);// goodconst leds = stage.selectAll('.led') .data(data) .enter().append('svg:svg') .classed('led', true) .attr('width', (radius + margin) * 2) .append('svg:g') .attr('transform', `translate(${radius + margin},${radius + margin})`) .call(tron.led);// goodconst leds = stage.selectAll('.led').data(data);const svg = leds.enter().append('svg:svg');svg.classed('led', true).attr('width', (radius + margin) * 2);const g = svg.append('svg:g');g.attr('transform', `translate(${radius + margin},${radius + margin})`).call(tron.led);``` - 19.7 Leave a blank line after blocks and before the next statement. ```javascript// badif (foo) { return bar;}return baz;// goodif (foo) { return bar;}return baz;// badconst obj = { foo() { }, bar() { },};return obj;// goodconst obj = { foo() { }, bar() { },};return obj;// badconst arr = [ function foo() { }, function bar() { },];return arr;// goodconst arr = [ function foo() { }, function bar() { },];return arr;``` - 19.8 Do not pad your blocks with blank lines. eslint: &lt;code&gt;padded-blocks&lt;/code&gt; ```javascript// badfunction bar() { console.log(foo);}// badif (baz) { console.log(qux);} else { console.log(foo);}// badclass Foo { constructor(bar) { this.bar = bar; }}// goodfunction bar() { console.log(foo);}// goodif (baz) { console.log(qux);} else { console.log(foo);}``` - 19.9 Do not use multiple blank lines to pad your code. eslint: &lt;code&gt;no-multiple-empty-lines&lt;/code&gt; &lt;!-- markdownlint-disable MD012 --&gt;```javascript// badclass Person { constructor(fullName, email, birthday) { this.fullName = fullName; this.email = email; this.setAge(birthday); } setAge(birthday) { const today = new Date(); const age = this.getAge(today, birthday); this.age = age; } getAge(today, birthday) { // .. }}// goodclass Person { constructor(fullName, email, birthday) { this.fullName = fullName; this.email = email; this.setAge(birthday); } setAge(birthday) { const today = new Date(); const age = getAge(today, birthday); this.age = age; } getAge(today, birthday) { // .. }}``` - 19.10 Do not add spaces inside parentheses. eslint: &lt;code&gt;space-in-parens&lt;/code&gt; ```javascript// badfunction bar( foo ) { return foo;}// goodfunction bar(foo) { return foo;}// badif ( foo ) { console.log(foo);}// goodif (foo) { console.log(foo);}``` - 19.11 Do not add spaces inside brackets. eslint: &lt;code&gt;array-bracket-spacing&lt;/code&gt; ```javascript// badconst foo = [ 1, 2, 3 ];console.log(foo[ 0 ]);// goodconst foo = [1, 2, 3];console.log(foo[0]);``` - 19.12 Add spaces inside curly braces. eslint: &lt;code&gt;object-curly-spacing&lt;/code&gt; ```javascript// badconst foo = {clark: 'kent'};// goodconst foo = { clark: 'kent' };``` - 19.13 Avoid having lines of code that are longer than 100 characters (including whitespace). Note: per above , long strings are exempt from this rule, and should not be broken up. eslint: &lt;code&gt;max-len&lt;/code&gt; &gt; Why? This ensures readability and maintainability.```javascript// badconst foo = jsonData && jsonData.foo && jsonData.foo.bar && jsonData.foo.bar.baz && jsonData.foo.bar.baz.quux && jsonData.foo.bar.baz.quux.xyzzy;// bad$.ajax({ method: 'POST', url: 'https://airbnb.com/', data: { name: 'John' } }).done(() =&gt; console.log('Congratulations!')).fail(() =&gt; console.log('You have failed this city.'));// goodconst foo = jsonData && jsonData.foo && jsonData.foo.bar && jsonData.foo.bar.baz && jsonData.foo.bar.baz.quux && jsonData.foo.bar.baz.quux.xyzzy;// good$.ajax({ method: 'POST', url: 'https://airbnb.com/', data: { name: 'John' },}) .done(() =&gt; console.log('Congratulations!')) .fail(() =&gt; console.log('You have failed this city.'));``` - 19.14 Require consistent spacing inside an open block token and the next token on the same line. This rule also enforces consistent spacing inside a close block token and previous token on the same line. eslint: &lt;code&gt;block-spacing&lt;/code&gt; ```javascript// badfunction foo() {return true;}if (foo) { bar = 0;}// goodfunction foo() { return true; }if (foo) { bar = 0; }``` - 19.15 Avoid spaces before commas and require a space after commas. eslint: &lt;code&gt;comma-spacing&lt;/code&gt; ```javascript// badvar foo = 1,bar = 2;var arr = [1 , 2];// goodvar foo = 1, bar = 2;var arr = [1, 2];``` - 19.16 Enforce spacing inside of computed property brackets. eslint: &lt;code&gt;computed-property-spacing&lt;/code&gt; ```javascript// badobj[foo ]obj[ 'foo']var x = {[ b ]: a}obj[foo[ bar ]]// goodobj[foo]obj['foo']var x = { [b]: a }obj[foo[bar]]``` - 19.17 Avoid spaces between functions and their invocations. eslint: &lt;code&gt;func-call-spacing&lt;/code&gt; ```javascript// badfunc ();func();// goodfunc();``` - 19.18 Enforce spacing between keys and values in object literal properties. eslint: &lt;code&gt;key-spacing&lt;/code&gt; ```javascript// badvar obj = { foo : 42 };var obj2 = { foo:42 };// goodvar obj = { foo: 42 };``` - 19.19 Avoid trailing spaces at the end of lines. eslint: &lt;code&gt;no-trailing-spaces&lt;/code&gt; - 19.20 Avoid multiple empty lines, only allow one newline at the end of files, and avoid a newline at the beginning of files. eslint: &lt;code&gt;no-multiple-empty-lines&lt;/code&gt; &lt;!-- markdownlint-disable MD012 --&gt;```javascript// bad - multiple empty linesvar x = 1;var y = 2;// bad - 2+ newlines at end of filevar x = 1;var y = 2;// bad - 1+ newline(s) at beginning of filevar x = 1;var y = 2;// goodvar x = 1;var y = 2;```&lt;!-- markdownlint-enable MD012 --&gt; ⬆ back to top Commas - 20.1 Leading commas: Nope. eslint: &lt;code&gt;comma-style&lt;/code&gt; ```javascript// badconst story = [ once , upon , aTime];// goodconst story = [ once, upon, aTime,];// badconst hero = { firstName: 'Ada' , lastName: 'Lovelace' , birthYear: 1815 , superPower: 'computers'};// goodconst hero = { firstName: 'Ada', lastName: 'Lovelace', birthYear: 1815, superPower: 'computers',};``` - 20.2 Additional trailing comma: Yup. eslint: &lt;code&gt;comma-dangle&lt;/code&gt; &gt; Why? This leads to cleaner git diffs. Also, transpilers like Babel will remove the additional trailing comma in the transpiled code which means you don’t have to worry about the [trailing comma problem](https://github.com/airbnb/javascript/blob/es5-deprecated/es5/README.md#commas) in legacy browsers.```diff// bad - git diff without trailing commaconst hero = { firstName: 'Florence',- lastName: 'Nightingale'+ lastName: 'Nightingale',+ inventorOf: ['coxcomb chart', 'modern nursing']};// good - git diff with trailing commaconst hero = { firstName: 'Florence', lastName: 'Nightingale',+ inventorOf: ['coxcomb chart', 'modern nursing'],};``````javascript// badconst hero = { firstName: 'Dana', lastName: 'Scully'};const heroes = [ 'Batman', 'Superman'];// goodconst hero = { firstName: 'Dana', lastName: 'Scully',};const heroes = [ 'Batman', 'Superman',];// badfunction createHero( firstName, lastName, inventorOf) { // does nothing}// goodfunction createHero( firstName, lastName, inventorOf,) { // does nothing}// good (note that a comma must not appear after a "rest" element)function createHero( firstName, lastName, inventorOf, ...heroArgs) { // does nothing}// badcreateHero( firstName, lastName, inventorOf);// goodcreateHero( firstName, lastName, inventorOf,);// good (note that a comma must not appear after a "rest" element)createHero( firstName, lastName, inventorOf, ...heroArgs);``` ⬆ back to top Semicolons - 21.1 Yup. eslint: &lt;code&gt;semi&lt;/code&gt; &gt; Why? When JavaScript encounters a line break without a semicolon, it uses a set of rules called [Automatic Semicolon Insertion](https://tc39.github.io/ecma262/#sec-automatic-semicolon-insertion) to determine whether it should regard that line break as the end of a statement, and (as the name implies) place a semicolon into your code before the line break if it thinks so. ASI contains a few eccentric behaviors, though, and your code will break if JavaScript misinterprets your line break. These rules will become more complicated as new features become a part of JavaScript. Explicitly terminating your statements and configuring your linter to catch missing semicolons will help prevent you from encountering issues.```javascript// bad - raises exceptionconst luke = {}const leia = {}[luke, leia].forEach((jedi) =&gt; jedi.father = 'vader')// bad - raises exceptionconst reaction = "No! That’s impossible!"(async function meanwhileOnTheFalcon() { // handle `leia`, `lando`, `chewie`, `r2`, `c3p0` // ...}())// bad - returns `undefined` instead of the value on the next line - always happens when `return` is on a line by itself because of ASI!function foo() { return 'search your feelings, you know it to be foo'}// goodconst luke = {};const leia = {};[luke, leia].forEach((jedi) =&gt; { jedi.father = 'vader';});// goodconst reaction = "No! That’s impossible!";(async function meanwhileOnTheFalcon() { // handle `leia`, `lando`, `chewie`, `r2`, `c3p0` // ...}());// goodfunction foo() { return 'search your feelings, you know it to be foo';}```[Read more](https://stackoverflow.com/questions/7365172/semicolon-before-self-invoking-function/7365214#7365214). ⬆ back to top Type Casting & Coercion - 22.1 Perform type coercion at the beginning of the statement. - 22.2 Strings: eslint: &lt;code&gt;no-new-wrappers&lt;/code&gt; ```javascript// =&gt; this.reviewScore = 9;// badconst totalScore = new String(this.reviewScore); // typeof totalScore is "object" not "string"// badconst totalScore = this.reviewScore + ''; // invokes this.reviewScore.valueOf()// badconst totalScore = this.reviewScore.toString(); // isn’t guaranteed to return a string// goodconst totalScore = String(this.reviewScore);``` - 22.3 Numbers: Use Number for type casting and parseInt always with a radix for parsing strings. eslint: &lt;code&gt;radix&lt;/code&gt; &lt;code&gt;no-new-wrappers&lt;/code&gt; &gt; Why? The `parseInt` function produces an integer value dictated by interpretation of the contents of the string argument according to the specified radix. Leading whitespace in string is ignored. If radix is `undefined` or `0`, it is assumed to be `10` except when the number begins with the character pairs `0x` or `0X`, in which case a radix of 16 is assumed. This differs from ECMAScript 3, which merely discouraged (but allowed) octal interpretation. Many implementations have not adopted this behavior as of 2013. And, because older browsers must be supported, always specify a radix.```javascriptconst inputValue = '4';// badconst val = new Number(inputValue);// badconst val = +inputValue;// badconst val = inputValue &gt;&gt; 0;// badconst val = parseInt(inputValue);// goodconst val = Number(inputValue);// goodconst val = parseInt(inputValue, 10);``` - 22.4 If for whatever reason you are doing something wild and parseInt is your bottleneck and need to use Bitshift for performance reasons , leave a comment explaining why and what you’re doing. ```javascript// good/** * parseInt was the reason my code was slow. * Bitshifting the String to coerce it to a * Number made it a lot faster. */const val = inputValue &gt;&gt; 0;``` - 22.5 Note: Be careful when using bitshift operations. Numbers are represented as 64-bit values , but bitshift operations always return a 32-bit integer ( source ). Bitshift can lead to unexpected behavior for integer values larger than 32 bits. Discussion . Largest signed 32-bit Int is 2,147,483,647: ```javascript2147483647 &gt;&gt; 0; // =&gt; 21474836472147483648 &gt;&gt; 0; // =&gt; -21474836482147483649 &gt;&gt; 0; // =&gt; -2147483647``` - 22.6 Booleans: eslint: &lt;code&gt;no-new-wrappers&lt;/code&gt; ```javascriptconst age = 0;// badconst hasAge = new Boolean(age);// goodconst hasAge = Boolean(age);// bestconst hasAge = !!age;``` ⬆ back to top Naming Conventions - 23.1 Avoid single letter names. Be descriptive with your naming. eslint: &lt;code&gt;id-length&lt;/code&gt; ```javascript// badfunction q() { // ...}// goodfunction query() { // ...}``` - 23.2 Use camelCase when naming objects, functions, and instances. eslint: &lt;code&gt;camelcase&lt;/code&gt; ```javascript// badconst OBJEcttsssss = {};const this_is_my_object = {};function c() {}// goodconst thisIsMyObject = {};function thisIsMyFunction() {}``` - 23.3 Use PascalCase only when naming constructors or classes. eslint: &lt;code&gt;new-cap&lt;/code&gt; ```javascript// badfunction user(options) { this.name = options.name;}const bad = new user({ name: 'nope',});// goodclass User { constructor(options) { this.name = options.name; }}const good = new User({ name: 'yup',});``` - 23.4 Do not use trailing or leading underscores. eslint: &lt;code&gt;no-underscore-dangle&lt;/code&gt; &gt; Why? JavaScript does not have the concept of privacy in terms of properties or methods. Although a leading underscore is a common convention to mean “private”, in fact, these properties are fully public, and as such, are part of your public API contract. This convention might lead developers to wrongly think that a change won’t count as breaking, or that tests aren’t needed. tl;dr: if you want something to be “private”, it must not be observably present.```javascript// badthis.__firstName__ = 'Panda';this.firstName_ = 'Panda';this._firstName = 'Panda';// goodthis.firstName = 'Panda';// good, in environments where WeakMaps are available// see https://kangax.github.io/compat-table/es6/#test-WeakMapconst firstNames = new WeakMap();firstNames.set(this, 'Panda');``` - 23.5 Don’t save references to this . Use arrow functions or Function#bind . ```javascript// badfunction foo() { const self = this; return function () { console.log(self); };}// badfunction foo() { const that = this; return function () { console.log(that); };}// goodfunction foo() { return () =&gt; { console.log(this); };}``` - 23.6 A base filename should exactly match the name of its default export. ```javascript// file 1 contentsclass CheckBox { // ...}export default CheckBox;// file 2 contentsexport default function fortyTwo() { return 42; }// file 3 contentsexport default function insideDirectory() {}// in some other file// badimport CheckBox from './checkBox'; // PascalCase import/export, camelCase filenameimport FortyTwo from './FortyTwo'; // PascalCase import/filename, camelCase exportimport InsideDirectory from './InsideDirectory'; // PascalCase import/filename, camelCase export// badimport CheckBox from './check_box'; // PascalCase import/export, snake_case filenameimport forty_two from './forty_two'; // snake_case import/filename, camelCase exportimport inside_directory from './inside_directory'; // snake_case import, camelCase exportimport index from './inside_directory/index'; // requiring the index file explicitlyimport insideDirectory from './insideDirectory/index'; // requiring the index file explicitly// goodimport CheckBox from './CheckBox'; // PascalCase export/import/filenameimport fortyTwo from './fortyTwo'; // camelCase export/import/filenameimport insideDirectory from './insideDirectory'; // camelCase export/import/directory name/implicit "index"// ^ supports both insideDirectory.js and insideDirectory/index.js``` - 23.7 Use camelCase when you export-default a function. Your filename should be identical to your function’s name. ```javascriptfunction makeStyleGuide() { // ...}export default makeStyleGuide;``` - 23.8 Use PascalCase when you export a constructor / class / singleton / function library / bare object. ```javascriptconst AirbnbStyleGuide = { es6: { },};export default AirbnbStyleGuide;``` - 23.9 Acronyms and initialisms should always be all uppercased, or all lowercased. &gt; Why? Names are for readability, not to appease a computer algorithm.```javascript// badimport SmsContainer from './containers/SmsContainer';// badconst HttpRequests = [ // ...];// goodimport SMSContainer from './containers/SMSContainer';// goodconst HTTPRequests = [ // ...];// also goodconst httpRequests = [ // ...];// bestimport TextMessageContainer from './containers/TextMessageContainer';// bestconst requests = [ // ...];``` - 23.10 You may optionally uppercase a constant only if it (1) is exported, (2) is a const (it can not be reassigned), and (3) the programmer can trust it (and its nested properties) to never change. &gt; Why? This is an additional tool to assist in situations where the programmer would be unsure if a variable might ever change. UPPERCASE_VARIABLES are letting the programmer know that they can trust the variable (and its properties) not to change.- What about all `const` variables? - This is unnecessary, so uppercasing should not be used for constants within a file. It should be used for exported constants however.- What about exported objects? - Uppercase at the top level of export (e.g. `EXPORTED_OBJECT.key`) and maintain that all nested properties do not change.```javascript// badconst PRIVATE_VARIABLE = 'should not be unnecessarily uppercased within a file';// badexport const THING_TO_BE_CHANGED = 'should obviously not be uppercased';// badexport let REASSIGNABLE_VARIABLE = 'do not use let with uppercase variables';// ---// allowed but does not supply semantic valueexport const apiKey = 'SOMEKEY';// better in most casesexport const API_KEY = 'SOMEKEY';// ---// bad - unnecessarily uppercases key while adding no semantic valueexport const MAPPING = { KEY: 'value'};// goodexport const MAPPING = { key: 'value'};``` ⬆ back to top Accessors - 24.1 Accessor functions for properties are not required. - 24.2 Do not use JavaScript getters/setters as they cause unexpected side effects and are harder to test, maintain, and reason about. Instead, if you do make accessor functions, use getVal() and setVal('hello') . ```javascript// badclass Dragon { get age() { // ... } set age(value) { // ... }}// goodclass Dragon { getAge() { // ... } setAge(value) { // ... }}``` - 24.3 If the property/method is a boolean , use isVal() or hasVal() . ```javascript// badif (!dragon.age()) { return false;}// goodif (!dragon.hasAge()) { return false;}``` - 24.4 It’s okay to create get() and set() functions, but be consistent. ```javascriptclass Jedi { constructor(options = {}) { const lightsaber = options.lightsaber || 'blue'; this.set('lightsaber', lightsaber); } set(key, val) { this[key] = val; } get(key) { return this[key]; }}``` ⬆ back to top Events - 25.1 When attaching data payloads to events (whether DOM events or something more proprietary like Backbone events), pass an object literal (also known as a "hash") instead of a raw value. This allows a subsequent contributor to add more data to the event payload without finding and updating every handler for the event. For example, instead of: ```javascript// bad$(this).trigger('listingUpdated', listing.id);// ...$(this).on('listingUpdated', (e, listingID) =&gt; { // do something with listingID});```prefer:```javascript// good$(this).trigger('listingUpdated', { listingID: listing.id });// ...$(this).on('listingUpdated', (e, data) =&gt; { // do something with data.listingID});``` ⬆ back to top jQuery - 26.1 Prefix jQuery object variables with a $ . ```javascript// badconst sidebar = $('.sidebar');// goodconst $sidebar = $('.sidebar');// goodconst $sidebarBtn = $('.sidebar-btn');``` - 26.2 Cache jQuery lookups. ```javascript// badfunction setSidebar() { $('.sidebar').hide(); // ... $('.sidebar').css({ 'background-color': 'pink', });}// goodfunction setSidebar() { const $sidebar = $('.sidebar'); $sidebar.hide(); // ... $sidebar.css({ 'background-color': 'pink', });}``` - 26.3 For DOM queries use Cascading $('.sidebar ul') or parent &gt; child $('.sidebar &gt; ul') . jsPerf - 26.4 Use find with scoped jQuery object queries. ```javascript// bad$('ul', '.sidebar').hide();// bad$('.sidebar').find('ul').hide();// good$('.sidebar ul').hide();// good$('.sidebar &gt; ul').hide();// good$sidebar.find('ul').hide();``` ⬆ back to top ECMAScript 5 Compatibility - 27.1 Refer to Kangax ’s ES5 compatibility table . ⬆ back to top ECMAScript 6+ (ES 2015+) Styles - 28.1 This is a collection of links to the various ES6+ features. Arrow Functions Classes Object Shorthand Object Concise Object Computed Properties Template Strings Destructuring Default Parameters Rest Array Spreads Let and Const Exponentiation Operator Iterators and Generators Modules 28.2 Do not use TC39 proposals that have not reached stage 3. Why? They are not finalized , and they are subject to change or to be withdrawn entirely. We want to use JavaScript, and proposals are not JavaScript yet. ⬆ back to top Standard Library The Standard Library contains utilities that are functionally broken but remain for legacy reasons. - 29.1 Use Number.isNaN instead of global isNaN . eslint: &lt;code&gt;no-restricted-globals&lt;/code&gt; &gt; Why? The global `isNaN` coerces non-numbers to numbers, returning true for anything that coerces to NaN.&gt; If this behavior is desired, make it explicit.```javascript// badisNaN('1.2'); // falseisNaN('1.2.3'); // true// goodNumber.isNaN('1.2.3'); // falseNumber.isNaN(Number('1.2.3')); // true``` - 29.2 Use Number.isFinite instead of global isFinite . eslint: &lt;code&gt;no-restricted-globals&lt;/code&gt; &gt; Why? The global `isFinite` coerces non-numbers to numbers, returning true for anything that coerces to a finite number.&gt; If this behavior is desired, make it explicit.```javascript// badisFinite('2e3'); // true// goodNumber.isFinite('2e3'); // falseNumber.isFinite(parseInt('2e3', 10)); // true``` ⬆ back to top Testing - 30.1 Yup. ```javascriptfunction foo() { return true;}``` - 30.2 No, but seriously : - Whichever testing framework you use, you should be writing tests! - Strive to write many small pure functions, and minimize where mutations occur. - Be cautious about stubs and mocks - they can make your tests more brittle. - We primarily use &lt;code&gt;mocha&lt;/code&gt; and &lt;code&gt;jest&lt;/code&gt; at Airbnb. &lt;code&gt;tape&lt;/code&gt; is also used occasionally for small, separate modules. - 100% test coverage is a good goal to strive for, even if it’s not always practical to reach it. - Whenever you fix a bug, write a regression test . A bug fixed without a regression test is almost certainly going to break again in the future. ⬆ back to top Performance On Layout & Web Performance String vs Array Concat Try/Catch Cost In a Loop Bang Function jQuery Find vs Context, Selector innerHTML vs textContent for script text Long String Concatenation Are JavaScript functions like &lt;code&gt;map()&lt;/code&gt;, &lt;code&gt;reduce()&lt;/code&gt;, and &lt;code&gt;filter()&lt;/code&gt; optimized for traversing arrays? Loading... ⬆ back to top Resources Learning ES6+ Latest ECMA spec ExploringJS ES6 Compatibility Table Comprehensive Overview of ES6 Features Read This Standard ECMA-262 Tools Code Style Linters ESlint - Airbnb Style .eslintrc JSHint - Airbnb Style .jshintrc Neutrino Preset - @neutrinojs/airbnb Other Style Guides Google JavaScript Style Guide Google JavaScript Style Guide (Old) jQuery Core Style Guidelines Principles of Writing Consistent, Idiomatic JavaScript StandardJS Other Styles Naming this in nested functions - Christian Johansen Conditional Callbacks - Ross Allen Popular JavaScript Coding Conventions on GitHub - JeongHoon Byun Multiple var statements in JavaScript, not superfluous - Ben Alman Further Reading Understanding JavaScript Closures - Angus Croll Basic JavaScript for the impatient programmer - Dr. Axel Rauschmayer You Might Not Need jQuery - Zack Bloom & Adam Schwartz ES6 Features - Luke Hoban Frontend Guidelines - Benjamin De Cock Books JavaScript: The Good Parts - Douglas Crockford JavaScript Patterns - Stoyan Stefanov Pro JavaScript Design Patterns - Ross Harmes and Dustin Diaz High Performance Web Sites: Essential Knowledge for Front-End Engineers - Steve Souders Maintainable JavaScript - Nicholas C. Zakas JavaScript Web Applications - Alex MacCaw Pro JavaScript Techniques - John Resig Smashing Node.js: JavaScript Everywhere - Guillermo Rauch Secrets of the JavaScript Ninja - John Resig and Bear Bibeault Human JavaScript - Henrik Joreteg Superhero.js - Kim Joar Bekkelund, Mads Mobæk, & Olav Bjorkoy JSBooks - Julien Bouquillon Third Party JavaScript - Ben Vinegar and Anton Kovalyov Effective JavaScript: 68 Specific Ways to Harness the Power of JavaScript - David Herman Eloquent JavaScript - Marijn Haverbeke You Don’t Know JS: ES6 & Beyond - Kyle Simpson Blogs JavaScript Weekly JavaScript, JavaScript... Bocoup Weblog Adequately Good NCZOnline Perfection Kills Ben Alman Dmitry Baranovskiy nettuts Podcasts JavaScript Air JavaScript Jabber ⬆ back to top In the Wild This is a list of organizations that are using this style guide. Send us a pull request and we'll add you to the list. 123erfasst : 123erfasst/javascript 4Catalyzer : 4Catalyzer/javascript Aan Zee : AanZee/javascript Airbnb : airbnb/javascript AloPeyk : AloPeyk AltSchool : AltSchool/javascript Apartmint : apartmint/javascript Ascribe : ascribe/javascript Avant : avantcredit/javascript Axept : axept/javascript Billabong : billabong/javascript Bisk : bisk Bonhomme : bonhommeparis/javascript Brainshark : brainshark/javascript CaseNine : CaseNine/javascript Cerner : Cerner Chartboost : ChartBoost/javascript-style-guide Coeur d'Alene Tribe : www.cdatribe-nsn.gov ComparaOnline : comparaonline/javascript Compass Learning : compasslearning/javascript-style-guide DailyMotion : dailymotion/javascript DoSomething : DoSomething/eslint-config Digitpaint digitpaint/javascript Drupal : www.drupal.org Ecosia : ecosia/javascript Evernote : evernote/javascript-style-guide Evolution Gaming : evolution-gaming/javascript EvozonJs : evozonjs/javascript ExactTarget : ExactTarget/javascript Flexberry : Flexberry/javascript-style-guide Gawker Media : gawkermedia General Electric : GeneralElectric/javascript Generation Tux : GenerationTux/javascript GoodData : gooddata/gdc-js-style GreenChef : greenchef/javascript Grooveshark : grooveshark/javascript Grupo-Abraxas : Grupo-Abraxas/javascript Happeo : happeo/javascript Honey : honeyscience/javascript How About We : howaboutwe/javascript HubSpot : HubSpot/javascript Hyper : hyperoslo/javascript-playbook InterCity Group : intercitygroup/javascript-style-guide Jam3 : Jam3/Javascript-Code-Conventions JSSolutions : JSSolutions/javascript Kaplan Komputing : kaplankomputing/javascript KickorStick : kickorstick Kinetica Solutions : kinetica/javascript LEINWAND : LEINWAND/javascript Lonely Planet : lonelyplanet/javascript M2GEN : M2GEN/javascript Mighty Spring : mightyspring/javascript MinnPost : MinnPost/javascript MitocGroup : MitocGroup/javascript Muber : muber National Geographic : natgeo NullDev : NullDevCo/JavaScript-Styleguide Nulogy : nulogy/javascript Orange Hill Development : orangehill/javascript Orion Health : orionhealth/javascript OutBoxSoft : OutBoxSoft/javascript Peerby : Peerby/javascript Pier 1 : Pier1/javascript Qotto : Qotto/javascript-style-guide React : facebook.github.io/react/contributing/how-to-contribute.html#style-guide REI : reidev/js-style-guide Ripple : ripple/javascript-style-guide Sainsbury’s Supermarkets : jsainsburyplc Shutterfly : shutterfly/javascript Sourcetoad : sourcetoad/javascript Springload : springload StratoDem Analytics : stratodem/javascript SteelKiwi Development : steelkiwi/javascript StudentSphere : studentsphere/javascript SwoopApp : swoopapp/javascript SysGarage : sysgarage/javascript-style-guide Syzygy Warsaw : syzygypl/javascript Target : target/javascript Terra : terra TheLadders : TheLadders/javascript The Nerdery : thenerdery/javascript-standards Tomify : tomprats Traitify : traitify/eslint-config-traitify T4R Technology : T4R-Technology/javascript UrbanSim : urbansim VoxFeed : VoxFeed/javascript-style-guide WeBox Studio : weboxstudio/javascript Weggo : Weggo/javascript Zillow : zillow/javascript ZocDoc : ZocDoc/javascript ⬆ back to top Translation This style guide is also available in other languages: Brazilian Portuguese : armoucar/javascript-style-guide Bulgarian : borislavvv/javascript Catalan : fpmweb/javascript-style-guide Chinese (Simplified) : lin-123/javascript Chinese (Traditional) : jigsawye/javascript French : nmussy/javascript-style-guide German : timofurrer/javascript-style-guide Italian : sinkswim/javascript-style-guide Japanese : mitsuruog/javascript-style-guide Korean : ParkSB/javascript-style-guide Russian : leonidlebedev/javascript-airbnb Spanish : paolocarrasco/javascript-style-guide Thai : lvarayut/javascript-style-guide Turkish : eraycetinay/javascript Ukrainian : ivanzusko/javascript Vietnam : dangkyokhoang/javascript-style-guide The JavaScript Style Guide Guide Reference Chat With Us About JavaScript Find us on gitter . Contributors View Contributors License (The MIT License) Copyright (c) 2012 Airbnb Permission is hereby granted, free of charge, to any person obtaininga copy of this software and associated documentation files (the'Software'), to deal in the Software without restriction, includingwithout limitation the rights to use, copy, modify, merge, publish,distribute, sublicense, and/or sell copies of the Software, and topermit persons to whom the Software is furnished to do so, subject tothe following conditions: The above copyright notice and this permission notice shall beincluded in all copies or substantial portions of the Software. THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND,EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OFMERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANYCLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THESOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. ⬆ back to top Amendments We encourage you to fork this guide and change the rules to fit your team’s style guide. Below, you may list some amendments to the style guide. This allows you to periodically update your style guide without having to deal with merge conflicts. }; To restore the repository download the bundle wget https://archive.org/download/github.com-airbnb-javascript_-_2022-05-24_16-08-24/airbnb-javascript_-_2022-05-24_16-08-24.bundle and run: git clone airbnb-javascript_-_2022-05-24_16-08-24.bundle Source: https://github.com/airbnb/javascript Uploader: airbnb Upload date: 2022-05-24