JavaScript Standard Style

One Style to Rule Them All

No decisions to make. No .jshintrc, .jscsrc, or .eslintrc files to manage. It just works.

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

• No configuration. The easiest way to enforce consistent style in your module/project. Just drop it in.
• Catch style errors before they're submitted in PRs. Saves precious code review time by eliminating back-and-forth between maintainer and contributor.

Adopting standard style means ranking the importance of community conventions higher than personal style, which does not make sense for 100% of projects and development cultures. At the same time, open source can be a hostile place for newbies. Setting up clear, automated contributor expectations makes a project healthier.

Install

npm install standard

Rules

• 2 spaces – for indentation
• Single quotes for strings – except to avoid escaping
• No unused variables – this one catches tons of bugs!
• No semicolons – It's fine. Really!
• Never start a line with ( or [
  • This is the only gotcha with omitting semicolons – automatically checked for you!
• Space after keywords if (condition) { ... }
• Space after function name function name (arg) { ... }
• Name the context variable self
  • var self = this
  • Accidental use of window.self is dissallowed (happens when var self = this is omitted)
• Always use === instead of ==
  • Except obj == null is allowed to check for null or undefined.
• Always handle the node.js err function parameter
• Always prefix browser globals with window – except document and navigator are okay
  • Prevents accidental use of poorly-named browser globals like open, length, event, and name.
• And more goodness – give standard a try today!

To get a better idea, take a look at a sample file written in JavaScript Standard Style, or check out some of the repositories that use standard.

Badge

Use this in one of your projects? Include one of these badges in your readme to let people know that your code is using the standard style.

[![js-standard-style](https://raw.githubusercontent.com/feross/standard/master/badge.png)](https://github.com/feross/standard)

[![js-standard-style](https://img.shields.io/badge/code%20style-standard-brightgreen.svg?style=flat-square)](https://github.com/feross/standard)

Usage

The easiest way to use JavaScript Standard Style to check your code is to install it globally as a Node command line program. To do so, simply run the following command in your terminal (flag -g installs standard globally on your system, omit it if you want to install in the current working directory):

npm install standard -g

After you've done that you should be able to use the standard program. The simplest use case would be checking the style of all JavaScript files in the current working directory:

$ standard
Error: Code style check failed:
  lib/torrent.js:950:11: Expected '===' and instead saw '=='.

Editor plugins

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

• Vim - Just install Syntastic.
• Sublime Text - Install Package Control, SublimeLinter, and SublimeLinter-contrib-standard.
• Atom - Install Linter and linter-js-standard.

What you might do if you're clever

1. Add it to package.json

{
  "name": "my-cool-package",
  "devDependencies": {
    "standard": "^3.0.0"
  },
  "scripts": {
    "test": "standard && node my-tests.js"
  }
}

2. Check style automatically when you run npm test

$ npm test
Error: Code style check failed:
  lib/torrent.js:950:11: Expected '===' and instead saw '=='.

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

FAQ

Why would 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 time in two ways:

• No configuration. The easiest way to enforce consistent style in your module/project. Just drop it in.
• Catch style errors before they're submitted in PRs. Saves precious code review time by eliminating back-and-forth between maintainer and contributor.

How do I ignore files?

The paths node_modules/, .git/, *.min.js, bundle.js, and coverage/ are automatically excluded when looking for .js files to style check.

Sometimes you need to ignore additional folders or specific minfied files. To do that, add a standard.ignore property to package.json:

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

Is there an automatic formatter?

Yes! Just run standard --format filename.js. This uses Max Ogden's automatic formatter standard-format, which can automatically fix most code style issues.

While most issues can be fixed, some, like not handling errors, must be fixed manually.

How do I hide a certain warning?

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

JavaScript Standard Style uses eslint and jscs under-the-hood and you can hide their warnings as you normally would if you used each linter directly.

To get verbose output (so you can find the particular rule name to ignore), run:

$ standard --verbose
Error: Code style check failed:
  routes/error.js:20:36: 'file' was used before it was defined. (eslint/no-use-before-define)
  routes/submit.js:85:2: Expected indentation of 2 characters (jscs/validateIndentation)

The first error is from eslint. Disable all checks on a specific line:

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

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

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

Or, disable the rule for multiple lines:

/*eslint-disable no-use-before-define */
// offending code here...
// offending code here...
// offending code here...
/*eslint-enable no-use-before-define */

The second error is from jscs. In this case, the rule name is "validateIndentation". You can hide it with a // jscs:disable validateIndentation comment. Re-enable with a // jscs:enable validateIndentation comment.

Can you please add more config options?

No. Use eslint or jscs directly if you want that.

Pro tip: Just use standard and move on. There are actual real problems that you could spend your time solving :p

Why can't I pipe standard to other tools?

standard prints to stderr. This means that tools that read from stdout won't be able to read its output. The solution is to make standard print to stdout instead:

standard 2>&1 | grep variable

What about Web Workers?

Web workers have a magic global variable called self. In regular JS files, standard won't let you use self directly, as it wants to prevent accidental use of window.self. But standard has no way of knowing when you are in a worker and therefore does not know when to allow usage of self directly.

Until we figure out a better solution, we recommend adding this to the top of workers:

/* global self */

This lets standard (as well as humans reading your code) know that self is a global in web worker code.

Is there a Git pre-commit hook for standard?

Funny you should ask!

#!/bin/sh
# Ensure all javascript files staged for commit pass standard code style
git diff --name-only --cached --relative | grep '\.js$' | xargs standard
exit $?

License

MIT. Copyright (c) Feross Aboukhadijeh.