JavaScript Standard Style

Sponsored by

English• Español (Latinoamérica)• Français• Bahasa Indonesia• Italiano (Italian)• Nhật Bản ngữ (Japanese)• 한국어 (Korean)• Português (Brasil)• Giản thể tiếng Trung (Simplified Chinese)• Phồn thể tiếng Trung (Taiwanese Mandarin)

JavaScript style guide, linter, and formatter

This module saves you (and others!) time in three ways:

• No configuration.The easiest way to enforce code quality in your project. No decisions to make. No.eslintrcfiles to manage. It just works.
• Automatically format code.Just runstandard --fixand say goodbye to messy or inconsistent code.
• Catch style issues & programmer errors early.Save precious code review time by eliminating back-and-forth between reviewer & contributor.

Give it a try by runningnpx standard --fixright now!

Table of Contents

• Quick start
  • Install
  • Usage
  • What you might do if you're clever
• FAQ
  • Why should I use JavaScript Standard Style?
  • Who uses JavaScript Standard Style?
  • Are there text editor plugins?
  • Is there a readme badge?
  • I disagree with rule X, can you change it?
  • But this isn't a real web standard!
  • Is there an automatic formatter?
  • How do I ignore files?
  • How do I disable a rule?
  • I use a library that pollutes the global namespace. How do I prevent "variable is not defined" errors?
  • How do I use experimental JavaScript (ES Next) features?
  • Can I use a JavaScript language variant, like Flow or TypeScript?
  • What about Mocha, Jest, Jasmine, QUnit, etc?
  • What about Web Workers and Service Workers?
  • What is the difference between warnings and errors?
  • Can I check code inside of Markdown or HTML files?
  • Is there a Gitpre-commithook?
  • How do I make the output all colorful and pretty?
  • Is there a Node.js API?
  • How do I contribute to StandardJS?

Install

The easiest way to use JavaScript Standard Style is to install it globally as a Node command line program. Run the following command in Terminal:

$ npm install standard --global

Or, you can installstandardlocally, for use in a single project:

$ npm install standard --save-dev

Note: To run the preceding commands,Node.jsandnpmmust be installed.

Usage

After you've installedstandard,you should be able to use thestandardprogram. The simplest use case would be checking the style of all JavaScript files in the current working directory:

$ standard
Error: Use JavaScript Standard Style
lib/torrent.js:950:11: Expected'==='and instead saw'=='.

If you've installedstandardlocally, run withnpxinstead:

$ npx standard

You can optionally pass in a directory (or directories) using the glob pattern. Be sure to quote paths containing glob patterns so that they are expanded by standardinstead of your shell:

$ standard"src/util/**/*.js""test/**/*.js"

Note:by defaultstandardwill look for all files matching the patterns: **/*.js,**/*.jsx.

What you might do if you're clever

1. Add it topackage.json

   {
   "name":"my-cool-package",
   "devDependencies":{
   "standard":"*"
   },
   "scripts":{
   "test":"standard && node my-tests.js"
   }
   }

2. Style is checked automatically when you runnpm test

   $ npmtest
   Error: Use JavaScript Standard Style
   lib/torrent.js:950:11: Expected'==='and instead saw'=='.

3. Never give style feedback on a pull request again!

Why should I use JavaScript Standard Style?

The beauty of JavaScript Standard Style is that it's simple. No one wants to maintain multiple hundred-line style configuration files for every module/project they work on. Enough of this madness!

This module saves you (and others!) time in three ways:

• No configuration.The easiest way to enforce consistent style in your project. Just drop it in.
• Automatically format code.Just runstandard --fixand say goodbye to messy or inconsistent code.
• Catch style issues & programmer errors early.Save precious code review time by eliminating back-and-forth between reviewer & contributor.

Adoptingstandardstyle means ranking the importance of code clarity and community conventions higher than personal style. This might not make sense for 100% of projects and development cultures, however open source can be a hostile place for newbies. Setting up clear, automated contributor expectations makes a project healthier.

For more info, see the conference talk"Write Perfect Code with Standard and ESLint".In this talk, you'll learn about linting, when to usestandardversuseslint,and howprettiercompares tostandard.

Who uses JavaScript Standard Style?

		Your Logo Here

In addition to companies, many community members usestandardon packages that aretoo numerous to list here.

standardis also the top-starred linter in GitHub's Clean Code Lintershowcase.

Are there text editor plugins?

First, installstandard.Then, install the appropriate plugin for your editor:

Sublime Text

UsingPackage Control,installSublimeLinterand SublimeLinter-contrib-standard.

For automatic formatting on save, installStandardFormat.

Atom

Installlinter-js-standard.

Alternatively, you can installlinter-js-standard-engine.Instead of bundling a version ofstandardit will automatically use the version installed in your current project. It will also work out of the box with other linters based onstandard-engine.

For automatic formatting, installstandard-formatter.For snippets, installstandardjs-snippets.

Visual Studio Code

Installvscode-standard.(Includes support for automatic formatting.)

For JS snippets, install:vscode-standardjs-snippets.For React snippets, installvscode-react-standard.

Vim

Installale.And add these lines to your.vimrcfile.

letg:ale_linters={
\'javascript':['standard'],
\}
letg:ale_fixers={'javascript':['standard']}

This sets standard as your only linter and fixer for javascript files and so prevents conflicts with eslint. For linting and automatic fi xing on save, add these lines to.vimrc:

letg:ale_lint_on_save=1
letg:ale_fix_on_save=1

Alternative plugins to consider includeneomakeandsyntastic,both of which have built-in support forstandard(though configuration may be necessary).

Emacs

InstallFlycheckand check out themanualto learn how to enable it in your projects.

Brackets

Search the extension registry for"Standard Code Style"and click "Install".

WebStorm (PhpStorm, IntelliJ, RubyMine, JetBrains, etc.)

WebStormrecently announced native support forstandarddirectly in the IDE.

If you still prefer to configurestandardmanually,follow this guide.This applies to all JetBrains products, including PhpStorm, IntelliJ, RubyMine, etc.

Is there a readme badge?

Yes! If you usestandardin your project, you can include one of these badges in your readme to let people know that your code is using the standard style.

[![JavaScript Style Guide](https://cdn.rawgit /standard/standard/master/badge.svg)](https://github /standard/standard)

[![JavaScript Style Guide](https://img.shields.io/badge/code_style-standard-brightgreen.svg)](https://standardjs)

I disagree with rule X, can you change it?

No. The whole point ofstandardis to save you time by avoiding bikesheddingabout code style. There are lots of debates online about tabs vs. spaces, etc. that will never be resolved. These debates just distract from getting stuff done. At the end of the day you have to 'just pick something', and that's the whole philosophy ofstandard-- its a bunch of sensible 'just pick something' opinions. Hopefully, users see the value in that over defending their own opinions.

There are a couple of similar packages for anyone who does not want to completely acceptstandard:

• semistandard- standard, with semicolons
• standardx- standard, with custom tweaks

If you really want to configure hundreds of ESLint rules individually, you can always useeslintdirectly with eslint-config-standardto layer your changes on top. standard-ejectcan help you migrate fromstandardtoeslintandeslint-config-standard.

Pro tip: Just usestandardand move on. There are actual real problems that you could spend your time solving!:P

But this isn't a real web standard!

Of course it's not! The style laid out here is not affiliated with any official web standards groups, which is why this repo is calledstandard/standardand not ECMA/standard.

The word "standard" has more meanings than just "web standard":-) For example:

• This module helps hold our code to a highstandard of quality.
• This module ensures that new contributors follow some basicstyle standards.

Is there an automatic formatter?

Yes! You can usestandard --fixto fix most issues automatically.

standard --fixis built intostandardfor maximum convenience. Most problems are fixable, but some errors (like forgetting to handle errors) must be fixed manually.

To save you time,standardoutputs the message "Run standard --fix to automatically fix some problems"when it detects problems that can be fixed automatically.

How do I ignore files?

Certain paths (node_modules/,coverage/,vendor/,*.min.js, and files/folders that begin with.like.git/) are automatically ignored.

Paths in a project's root.gitignorefile are also automatically ignored.

Sometimes you need to ignore additional folders or specific minified files. To do that, add astandard.ignoreproperty topackage.json:

"standard":{
"ignore":[
"**/out/",
"/lib/select2/",
"/lib/ckeditor/",
"tmp.js"
]
}

How do I disable a rule?

In rare cases, you'll need to break a rule and hide the error generated by standard.

JavaScript Standard Style usesESLintunder-the-hood and you can hide errors as you normally would if you used ESLint directly.

Disableall ruleson a specific line:

file='I know what I am doing'// eslint-disable-line

Or, disableonlythe"no-use-before-define"rule:

file='I know what I am doing'// eslint-disable-line no-use-before-define

Or, disable the"no-use-before-define"rule formultiple lines:

/* eslint-disable no-use-before-define */
console.log('offending code goes here...')
console.log('offending code goes here...')
console.log('offending code goes here...')
/* eslint-enable no-use-before-define */

I use a library that pollutes the global namespace. How do I prevent "variable is not defined" errors?

Some packages (e.g.mocha) put their functions (e.g.describe,it) on the global object (poor form!). Since these functions are not defined orrequire'd anywhere in your code,standardwill warn that you're using a variable that is not defined (usually, this rule is really useful for catching typos!). But we want to disable it for these global variables.

To letstandard(as well as humans reading your code) know that certain variables are global in your code, add this to the top of your file:

/* global myVar1, myVar2 */

If you have hundreds of files, it may be desirable to avoid adding comments to every file. In this case, run:

$ standard --global myVar1 --global myVar2

Or, add this topackage.json:

{
"standard":{
"globals":["myVar1","myVar2"]
}
}

Note:globalandglobalsare equivalent.

How do I use experimental JavaScript (ES Next) features?

standardsupports the latest ECMAScript features, ES8 (ES2017), including language feature proposals that are in "Stage 4" of the proposal process.

To support experimental language features,standardsupports specifying a custom JavaScript parser. Before using a custom parser, consider whether the added complexity is worth it.

To use a custom parser, first install it from npm:

npm install @babel/eslint-parser --save-dev

Then run:

$ standard --parser @babel/eslint-parser

Or, add this topackage.json:

{
"standard":{
"parser":"@babel/eslint-parser"
}
}

Can I use a JavaScript language variant, like Flow or TypeScript?

standardsupports the latest ECMAScript features. However, Flow and TypeScript add new syntax to the language, so they are not supported out-of-the-box.

For TypeScript, an official variantts-standardis supported and maintained that provides a very similar experience tostandard.

For other JavaScript language variants,standardsupports specifying a custom JavaScript parser as well as an ESLint plugin to handle the changed syntax. Before using a JavaScript language variant, consider whether the added complexity is worth it.

TypeScript

ts-standardis the officially supported variant for TypeScript.ts-standardsupports all the same rules and options asstandardand includes additional TypeScript specific rules.ts-standardwill even lint regularjavascriptfiles by setting the configuration intsconfig.json.

npm install ts-standard --save-dev

Then run (wheretsconfig.jsonis located in the working directory):

$ ts-standard

Or, add this topackage.json:

{
"ts-standard":{
"project":"./tsconfig.json"
}
}

Note: To include additional files in linting such as test files, create atsconfig.eslint.jsonfile to use instead.

If you really want to configure hundreds of ESLint rules individually, you can always use eslint directly witheslint-config-standard-with-typescript to layer your changes on top.

Flow

To use Flow, you need to runstandardwith@babel/eslint-parseras the parser and eslint-plugin-flowtypeas a plugin.

npm install @babel/eslint-parser eslint-plugin-flowtype --save-dev

Then run:

$ standard --parser @babel/eslint-parser --plugin flowtype

Or, add this topackage.json:

{
"standard":{
"parser":"@babel/eslint-parser",
"plugins":["flowtype"]
}
}

Note:pluginandpluginsare equivalent.

What about Mocha, Jest, Jasmine, QUnit, etc?

To support mocha in test files, add this to the top of the test files:

/* eslint-env mocha */

Or, run:

$ standard --env mocha

Wheremochacan be one ofjest,jasmine,qunit,phantomjs,and so on. To see a full list, check ESLint's specifying environments documentation. For a list of what globals are available for these environments, check the globalsnpm module.

Note:envandenvsare equivalent.

What about Web Workers and Service Workers?

Add this to the top of web worker files:

/* eslint-env worker */

This letsstandard(as well as humans reading the code) know thatselfis a global in web worker code.

For Service workers, add this instead:

/* eslint-env serviceworker */

What is the difference between warnings and errors?

standardtreats all rule violations as errors, which means thatstandard will exit with a non-zero (error) exit code.

However, we may occasionally release a new major version ofstandard which changes a rule that affects the majority ofstandardusers (for example, transitioning fromvartolet/const). We do this only when we think the advantage is worth the cost and only when the rule is auto-fixable.

In these situations, we have a "transition period" where the rule change is only a "warning". Warnings don't causestandardto return a non-zero (error) exit code. However, a warning message will still print to the console. During the transition period,using standard --fixwill update your code so that it's ready for the next major version.

The slow and careful approach is what we strive for withstandard.We're generally extremely conservative in enforcing the usage of new language features. We want usingstandardto be light and fun and so we're careful about making changes that may get in your way. As always, you can disable a ruleat any time, if necessary.

Can I check code inside of Markdown or HTML files?

To check code inside Markdown files, usestandard-markdown.

Alternatively, there are ESLint plugins that can check code inside Markdown, HTML, and many other types of language files:

To check code inside Markdown files, use an ESLint plugin:

$ npm install eslint-plugin-markdown

Then, to check JS that appears inside code blocks, run:

$ standard --plugin markdown'**/*.md'

To check code inside HTML files, use an ESLint plugin:

$ npm install eslint-plugin-html

Then, to check JS that appears inside<script>tags, run:

$ standard --plugin html'**/*.html'

Is there a Gitpre-commithook?

Yes! Hooks are great for ensuring that unstyled code never even makes it into your repo. Never give style feedback on a pull request again!

You even have a choice...

Install your own hook

#!/bin/bash

#Ensure all JavaScript files staged for commit pass standard code style
functionxargs-r(){
#Portable version of "xargs -r". The -r flag is a GNU extension that
#prevents xargs from running if there are no input files.
ifIFS=read-r -d$'\n'path;then
echo"$path"|cat -|xargs"$@"
fi
}
git diff --name-only --cached --relative|grep'\.jsx\?$'|sed's/[^[:alnum:]]/\\&/g'|xargs-r -E''-t standard
if[[$?-ne0 ]];then
echo'JavaScript Standard Style errors were detected. Aborting commit.'
exit1
fi

Use apre-commithook

Thepre-commitlibrary allows hooks to be declared within a.pre-commit-config.yamlconfiguration file in the repo, and therefore more easily maintained across a team.

Users of pre-commit can simply addstandardto their.pre-commit-config.yamlfile, which will automatically fix.js,.jsx,.mjsand.cjsfiles:

-repo:https://github /standard/standard
rev:master
hooks:
-id:standard

Alternatively, for more advanced styling configurations, usestandardwithin theeslint hook:

-repo:https://github /pre-commit/mirrors-eslint
rev:master
hooks:
-id:eslint
files:\.[jt]sx?$#*.js, *.jsx, *.ts and *.tsx
types:[file]
additional_dependencies:
-eslint@latest
-eslint-config-standard@latest
#and whatever other plugins...

How do I make the output all colorful and pretty?

The built-in output is simple and straightforward, but if you like shiny things, installsnazzy:

$ npm install snazzy

And run:

$ standard|snazzy

There's alsostandard-tap, standard-json, standard-reporter,and standard-summary.

Is there a Node.js API?

Yes!

async standard.lintText(text, [opts])

Lint the provided sourcetext.Anoptsobject may be provided:

{
// unique to lintText
filename:'',// path of file containing the text being linted

// common to lintText and lintFiles
cwd:'',// current working directory (default: process.cwd())
fix:false,// automatically fix problems
extensions:[],// file extensions to lint (has sane defaults)
globals:[],// custom global variables to declare
plugins:[],// custom eslint plugins
envs:[],// custom eslint environment
parser:'',// custom js parser (e.g. babel-eslint)
usePackageJson:true,// use options from nearest package.json?
useGitIgnore:true// use file ignore patterns from.gitignore?
}

All options are optional, though some ESLint plugins require thefilenameoption.

Additional options may be loaded from apackage.jsonif it's found for the current working directory. See below for further details.

Returns aPromiseresolving to theresultsor rejected with anError.

Theresultsobject will contain the following properties:

constresults={
results:[
{
filePath:'',
messages:[
{ruleId:'',message:'',line:0,column:0}
],
errorCount:0,
warningCount:0,
output:''// fixed source code (only present with {fix: true} option)
}
],
errorCount:0,
warningCount:0
}

async standard.lintFiles(files, [opts])

Lint the providedfilesglobs. Anoptsobject may be provided:

{
// unique to lintFiles
ignore:[],// file globs to ignore (has sane defaults)

// common to lintText and lintFiles
cwd:'',// current working directory (default: process.cwd())
fix:false,// automatically fix problems
extensions:[],// file extensions to lint (has sane defaults)
globals:[],// custom global variables to declare
plugins:[],// custom eslint plugins
envs:[],// custom eslint environment
parser:'',// custom js parser (e.g. babel-eslint)
usePackageJson:true,// use options from nearest package.json?
useGitIgnore:true// use file ignore patterns from.gitignore?
}

Additional options may be loaded from apackage.jsonif it's found for the current working directory. See below for further details.

Bothignoreandfilespatterns are resolved relative to the current working directory.

Returns aPromiseresolving to theresultsor rejected with anError(same as above).

How do I contribute to StandardJS?

Contributions are welcome! Check out theissuesor thePRs,and make your own if you want something that you don't see there.

Want to chat?Join contributors on Discord.

Here are some important packages in thestandardecosystem:

• standard- this repo
  • standard-engine- cli engine for arbitrary eslint rules
  • eslint-config-standard- eslint rules for standard
  • eslint-config-standard-jsx- eslint rules for standard (JSX)
  • eslint- the linter that powers standard
• snazzy- pretty terminal output for standard
• standard-www- code forhttps://standardjs
• semistandard- standard, with semicolons (if you must)
• standardx- standard, with custom tweaks

There are also manyeditor plugins,a list of npm packages that usestandard, and an awesome list of packages in thestandardecosystem.

Security Policies and Procedures

Thestandardteam and community take all security bugs instandardseriously. Please see oursecurity policies and proceduresdocument to learn how to report issues.

License

MIT.Copyright (c)Feross Aboukhadijeh.