A mostly reasonable approach to JavaScript
- Types
- Objects
- Arrays
- Strings
- Functions
- Properties
- Variables
- Hoisting
- Comparison Operators & Equality
- Blocks
- Comments
- Whitespace
- Commas
- Semicolons
- Type Casting & Coercion
- Naming Conventions
- Accessors
- Constructors
- Events
- Modules
- jQuery
- ECMAScript 5 Compatibility
- Testing
- Performance
- Resources
- In the Wild
- Translation
- The JavaScript Style Guide Guide
- Chat With Us About Javascript
- Contributors
- License
-
Primitives: When you access a primitive type you work directly on its value.
stringnumberbooleannullundefined
var foo = 1; var bar = foo; bar = 9; console.log(foo, bar); // => 1, 9
-
Complex: When you access a complex type you work on a reference to its value.
objectarrayfunction
var foo = [1, 2]; var bar = foo; bar[0] = 9; console.log(foo[0], bar[0]); // => 9, 9
-
Use the literal syntax for object creation.
// bad var item = new Object(); // good var item = {};
-
Don't use reserved words as keys. It won't work in IE8. More info.
// bad var superman = { default: { clark: 'kent' }, private: true }; // good var superman = { defaults: { clark: 'kent' }, hidden: true };
-
Use readable synonyms in place of reserved words.
// bad var superman = { class: 'alien' }; // bad var superman = { klass: 'alien' }; // good var superman = { type: 'alien' };
-
Use the literal syntax for array creation.
// bad var items = new Array(); // good var items = [];
-
If you don't know array length use Array#push.
var someStack = []; // bad someStack[someStack.length] = 'abracadabra'; // good someStack.push('abracadabra');
-
When you need to copy an array use Array#slice. jsPerf
var len = items.length; var itemsCopy = []; var i; // bad for (i = 0; i < len; i++) { itemsCopy[i] = items[i]; } // good itemsCopy = items.slice();
-
To convert an array-like object to an array, use Array#slice.
function trigger() { var args = Array.prototype.slice.call(arguments); ... }
-
Use single quotes
''for strings.// bad var name = "Bob Parr"; // good var name = 'Bob Parr'; // bad var fullName = "Bob " + this.lastName; // good var fullName = 'Bob ' + this.lastName;
-
Strings longer than 80 characters should be written across multiple lines using string concatenation.
-
Note: If overused, long strings with concatenation could impact performance. jsPerf & Discussion.
// bad var 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.'; // bad var 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.'; // good var 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.';
-
When programmatically building up a string, use Array#join instead of string concatenation. Mostly for IE: jsPerf.
var items; var messages; var length; var i; messages = [{ state: 'success', message: 'This one worked.' }, { state: 'success', message: 'This one worked as well.' }, { state: 'error', message: 'This one did not work.' }]; length = messages.length; // bad function inbox(messages) { items = '<ul>'; for (i = 0; i < length; i++) { items += '<li>' + messages[i].message + '</li>'; } return items + '</ul>'; } // good function inbox(messages) { items = []; for (i = 0; i < length; i++) { items[i] = '<li>' + messages[i].message + '</li>'; } return '<ul>' + items.join('') + '</ul>'; }
-
Function expressions:
// anonymous function expression var anonymous = function() { return true; }; // named function expression var named = function named() { return true; }; // immediately-invoked function expression (IIFE) (function() { console.log('Welcome to the Internet. Please follow me.'); })();
-
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.
-
Note: ECMA-262 defines a
blockas a list of statements. A function declaration is not a statement. Read ECMA-262's note on this issue.// bad if (currentUser) { function test() { console.log('Nope.'); } } // good var test; if (currentUser) { test = function test() { console.log('Yup.'); }; }
-
Never name a parameter
arguments, this will take precedence over theargumentsobject that is given to every function scope.// bad function nope(name, options, arguments) { // ...stuff... } // good function yup(name, options, args) { // ...stuff... }
-
Use dot notation when accessing properties.
var luke = { jedi: true, age: 28 }; // bad var isJedi = luke['jedi']; // good var isJedi = luke.jedi;
-
Use subscript notation
[]when accessing properties with a variable.var luke = { jedi: true, age: 28 }; function getProp(prop) { return luke[prop]; } var isJedi = getProp('jedi');
-
Always use
varto declare variables. Not doing so will result in global variables. We want to avoid polluting the global namespace. Captain Planet warned us of that.// bad superPower = new SuperPower(); // good var superPower = new SuperPower();
-
Use one
vardeclaration per variable. 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.// bad var items = getItems(), goSportsTeam = true, dragonball = 'z'; // bad // (compare to above, and try to spot the mistake) var items = getItems(), goSportsTeam = true; dragonball = 'z'; // good var items = getItems(); var goSportsTeam = true; var dragonball = 'z';
-
Declare unassigned variables last. This is helpful when later on you might need to assign a variable depending on one of the previous assigned variables.
// bad var i, len, dragonball, items = getItems(), goSportsTeam = true; // bad var i; var items = getItems(); var dragonball; var goSportsTeam = true; var len; // good var items = getItems(); var goSportsTeam = true; var dragonball; var length; var i;
-
Assign variables at the top of their scope. This helps avoid issues with variable declaration and assignment hoisting related issues.
// bad function() { test(); console.log('doing stuff..'); //..other stuff.. var name = getName(); if (name === 'test') { return false; } return name; } // good function() { var name = getName(); test(); console.log('doing stuff..'); //..other stuff.. if (name === 'test') { return false; } return name; } // bad function() { var name = getName(); if (!arguments.length) { return false; } return true; } // good function() { if (!arguments.length) { return false; } var name = getName(); return true; }
-
Variable declarations get hoisted to the top of their scope, their assignment does not.
// we know this wouldn't work (assuming there // is no notDefined global variable) function example() { console.log(notDefined); // => 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); // => 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() { var declaredButNotAssigned; console.log(declaredButNotAssigned); // => undefined declaredButNotAssigned = true; }
-
Anonymous function expressions hoist their variable name, but not the function assignment.
function example() { console.log(anonymous); // => undefined anonymous(); // => TypeError anonymous is not a function var anonymous = function() { console.log('anonymous function expression'); }; }
-
Named function expressions hoist the variable name, not the function name or the function body.
function example() { console.log(named); // => undefined named(); // => TypeError named is not a function superPower(); // => 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); // => undefined named(); // => TypeError named is not a function var named = function named() { console.log('named'); } }
-
Function declarations hoist their name and the function body.
function example() { superPower(); // => Flying function superPower() { console.log('Flying'); } }
-
For more information refer to JavaScript Scoping & Hoisting by Ben Cherry.
-
Use
===and!==over==and!=. -
Comparison operators are evaluated using coercion with the
ToBooleanmethod 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
if ([0]) { // true // An array is an object, objects evaluate to true }
-
Use shortcuts.
// bad if (name !== '') { // ...stuff... } // good if (name) { // ...stuff... } // bad if (collection.length > 0) { // ...stuff... } // good if (collection.length) { // ...stuff... }
-
For more information see Truth Equality and JavaScript by Angus Croll.
-
Use braces with all multi-line blocks.
// bad if (test) return false; // good if (test) return false; // good if (test) { return false; } // bad function() { return false; } // good function() { return false; }
-
If you're using multi-line blocks with
ifandelse, putelseon the same line as yourifblock's closing brace.// bad if (test) { thing1(); thing2(); } else { thing3(); } // good if (test) { thing1(); thing2(); } else { thing3(); }
-
Use
/** ... */for multiline comments. Include a description, specify types and values for all parameters and return values.// bad // make() returns a new element // based on the passed in tag name // // @param {String} tag // @return {Element} element function make(tag) { // ...stuff... return element; } // good /** * make() returns a new element * based on the passed in tag name * * @param {String} tag * @return {Element} element */ function make(tag) { // ...stuff... return element; }
-
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.// bad var active = true; // is current tab // good // is current tab var active = true; // bad function getType() { console.log('fetching type...'); // set the default type to 'no type' var type = this._type || 'no type'; return type; } // good function getType() { console.log('fetching type...'); // set the default type to 'no type' var type = this._type || 'no type'; return type; }
-
Prefixing your comments with
FIXMEorTODOhelps 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 areFIXME -- need to figure this outorTODO -- need to implement. -
Use
// FIXME:to annotate problems.function Calculator() { // FIXME: shouldn't use a global here total = 0; return this; }
-
Use
// TODO:to annotate solutions to problems.function Calculator() { // TODO: total should be configurable by an options param this.total = 0; return this; }
**[⬆ back to top](#table-of-contents)**
## Whitespace
- Use soft tabs set to 2 spaces.
```javascript
// bad
function() {
∙∙∙∙var name;
}
// bad
function() {
∙var name;
}
// good
function() {
∙∙var name;
}
```
- Place 1 space before the leading brace.
```javascript
// bad
function test(){
console.log('test');
}
// good
function test() {
console.log('test');
}
// bad
dog.set('attr',{
age: '1 year',
breed: 'Bernese Mountain Dog'
});
// good
dog.set('attr', {
age: '1 year',
breed: 'Bernese Mountain Dog'
});
```
- Place 1 space before the opening parenthesis in control statements (`if`, `while` etc.). Place no space before the argument list in function calls and declarations.
```javascript
// bad
if(isJedi) {
fight ();
}
// good
if (isJedi) {
fight();
}
// bad
function fight () {
console.log ('Swooosh!');
}
// good
function fight() {
console.log('Swooosh!');
}
```
- Set off operators with spaces.
```javascript
// bad
var x=y+5;
// good
var x = y + 5;
```
- End files with a single newline character.
```javascript
// bad
(function(global) {
// ...stuff...
})(this);
```
```javascript
// bad
(function(global) {
// ...stuff...
})(this);↵
↵
```
```javascript
// good
(function(global) {
// ...stuff...
})(this);↵
```
- Use indentation when making long method chains. Use a leading dot, which
emphasizes that the line is a method call, not a new statement.
```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();
// bad
var leds = stage.selectAll('.led').data(data).enter().append('svg:svg').class('led', true)
.attr('width', (radius + margin) * 2).append('svg:g')
.attr('transform', 'translate(' + (radius + margin) + ',' + (radius + margin) + ')')
.call(tron.led);
// good
var leds = stage.selectAll('.led')
.data(data)
.enter().append('svg:svg')
.class('led', true)
.attr('width', (radius + margin) * 2)
.append('svg:g')
.attr('transform', 'translate(' + (radius + margin) + ',' + (radius + margin) + ')')
.call(tron.led);
```
- Leave a blank line after blocks and before the next statement
```javascript
// bad
if (foo) {
return bar;
}
return baz;
// good
if (foo) {
return bar;
}
return baz;
// bad
var obj = {
foo: function() {
},
bar: function() {
}
};
return obj;
// good
var obj = {
foo: function() {
},
bar: function() {
}
};
return obj;
```
**[⬆ back to top](#table-of-contents)**
## Commas
- Leading commas: **Nope.**
```javascript
// bad
var story = [
once
, upon
, aTime
];
// good
var story = [
once,
upon,
aTime
];
// bad
var hero = {
firstName: 'Bob'
, lastName: 'Parr'
, heroName: 'Mr. Incredible'
, superPower: 'strength'
};
// good
var hero = {
firstName: 'Bob',
lastName: 'Parr',
heroName: 'Mr. Incredible',
superPower: 'strength'
};
```
- Additional trailing comma: **Nope.** This can cause problems with IE6/7 and IE9 if it's in quirksmode. Also, in some implementations of ES3 would add length to an array if it had an additional trailing comma. This was clarified in ES5 ([source](http://es5.github.io/#D)):
> Edition 5 clarifies the fact that a trailing comma at the end of an ArrayInitialiser does not add to the length of the array. This is not a semantic change from Edition 3 but some implementations may have previously misinterpreted this.
```javascript
// bad
var hero = {
firstName: 'Kevin',
lastName: 'Flynn',
};
var heroes = [
'Batman',
'Superman',
];
// good
var hero = {
firstName: 'Kevin',
lastName: 'Flynn'
};
var heroes = [
'Batman',
'Superman'
];
```
**[⬆ back to top](#table-of-contents)**
## Semicolons
- **Yup.**
```javascript
// bad
(function() {
var name = 'Skywalker'
return name
})()
// good
(function() {
var name = 'Skywalker';
return name;
})();
// good (guards against the function becoming an argument when two files with IIFEs are concatenated)
;(function() {
var name = 'Skywalker';
return name;
})();
```
[Read more](http://stackoverflow.com/a/7365214/1712802).
**[⬆ back to top](#table-of-contents)**
## Type Casting & Coercion
- Perform type coercion at the beginning of the statement.
- Strings:
```javascript
// => this.reviewScore = 9;
// bad
var totalScore = this.reviewScore + '';
// good
var totalScore = '' + this.reviewScore;
// bad
var totalScore = '' + this.reviewScore + ' total score';
// good
var totalScore = this.reviewScore + ' total score';
```
- Use `parseInt` for Numbers and always with a radix for type casting.
```javascript
var inputValue = '4';
// bad
var val = new Number(inputValue);
// bad
var val = +inputValue;
// bad
var val = inputValue >> 0;
// bad
var val = parseInt(inputValue);
// good
var val = Number(inputValue);
// good
var val = parseInt(inputValue, 10);
```
- If for whatever reason you are doing something wild and `parseInt` is your bottleneck and need to use Bitshift for [performance reasons](http://jsperf.com/coercion-vs-casting/3), 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.
*/
var val = inputValue >> 0;
```
- **Note:** Be careful when using bitshift operations. Numbers are represented as [64-bit values](http://es5.github.io/#x4.3.19), but Bitshift operations always return a 32-bit integer ([source](http://es5.github.io/#x11.7)). Bitshift can lead to unexpected behavior for integer values larger than 32 bits. [Discussion](https://github.com/airbnb/javascript/issues/109). Largest signed 32-bit Int is 2,147,483,647:
```javascript
2147483647 >> 0 //=> 2147483647
2147483648 >> 0 //=> -2147483648
2147483649 >> 0 //=> -2147483647
```
- Booleans:
```javascript
var age = 0;
// bad
var hasAge = new Boolean(age);
// good
var hasAge = Boolean(age);
// good
var hasAge = !!age;
```
**[⬆ back to top](#table-of-contents)**
## Naming Conventions
- Avoid single letter names. Be descriptive with your naming.
```javascript
// bad
function q() {
// ...stuff...
}
// good
function query() {
// ..stuff..
}
```
- Use camelCase when naming objects, functions, and instances.
```javascript
// bad
var OBJEcttsssss = {};
var this_is_my_object = {};
function c() {}
var u = new user({
name: 'Bob Parr'
});
// good
var thisIsMyObject = {};
function thisIsMyFunction() {}
var user = new User({
name: 'Bob Parr'
});
```
- Use PascalCase when naming constructors or classes.
```javascript
// bad
function user(options) {
this.name = options.name;
}
var bad = new user({
name: 'nope'
});
// good
function User(options) {
this.name = options.name;
}
var good = new User({
name: 'yup'
});
```
- Use a leading underscore `_` when naming private properties.
```javascript
// bad
this.__firstName__ = 'Panda';
this.firstName_ = 'Panda';
// good
this._firstName = 'Panda';
```
- When saving a reference to `this` use `_this`.
```javascript
// bad
function() {
var self = this;
return function() {
console.log(self);
};
}
// bad
function() {
var that = this;
return function() {
console.log(that);
};
}
// good
function() {
var _this = this;
return function() {
console.log(_this);
};
}
```
- Name your functions. This is helpful for stack traces.
```javascript
// bad
var log = function(msg) {
console.log(msg);
};
// good
var log = function log(msg) {
console.log(msg);
};
```
- **Note:** IE8 and below exhibit some quirks with named function expressions. See [http://kangax.github.io/nfe/](http://kangax.github.io/nfe/) for more info.
- If your file exports a single class, your filename should be exactly the name of the class.
```javascript
// file contents
class CheckBox {
// ...
}
module.exports = CheckBox;
// in some other file
// bad
var CheckBox = require('./checkBox');
// bad
var CheckBox = require('./check_box');
// good
var CheckBox = require('./CheckBox');
```
**[⬆ back to top](#table-of-contents)**
## Accessors
- Accessor functions for properties are not required.
- If you do make accessor functions use getVal() and setVal('hello').
```javascript
// bad
dragon.age();
// good
dragon.getAge();
// bad
dragon.age(25);
// good
dragon.setAge(25);
```
- If the property is a boolean, use isVal() or hasVal().
```javascript
// bad
if (!dragon.age()) {
return false;
}
// good
if (!dragon.hasAge()) {
return false;
}
```
- It's okay to create get() and set() functions, but be consistent.
```javascript
function Jedi(options) {
options || (options = {});
var lightsaber = options.lightsaber || 'blue';
this.set('lightsaber', lightsaber);
}
Jedi.prototype.set = function(key, val) {
this[key] = val;
};
Jedi.prototype.get = function(key) {
return this[key];
};
```
**[⬆ back to top](#table-of-contents)**
## Constructors
- Assign methods to the prototype object, instead of overwriting the prototype with a new object. Overwriting the prototype makes inheritance impossible: by resetting the prototype you'll overwrite the base!
```javascript
function Jedi() {
console.log('new jedi');
}
// bad
Jedi.prototype = {
fight: function fight() {
console.log('fighting');
},
block: function block() {
console.log('blocking');
}
};
// good
Jedi.prototype.fight = function fight() {
console.log('fighting');
};
Jedi.prototype.block = function block() {
console.log('blocking');
};
```
- Methods can return `this` to help with method chaining.
```javascript
// bad
Jedi.prototype.jump = function() {
this.jumping = true;
return true;
};
Jedi.prototype.setHeight = function(height) {
this.height = height;
};
var luke = new Jedi();
luke.jump(); // => true
luke.setHeight(20); // => undefined
// good
Jedi.prototype.jump = function() {
this.jumping = true;
return this;
};
Jedi.prototype.setHeight = function(height) {
this.height = height;
return this;
};
var luke = new Jedi();
luke.jump()
.setHeight(20);
```
- It's okay to write a custom toString() method, just make sure it works successfully and causes no side effects.
```javascript
function Jedi(options) {
options || (options = {});
this.name = options.name || 'no name';
}
Jedi.prototype.getName = function getName() {
return this.name;
};
Jedi.prototype.toString = function toString() {
return 'Jedi - ' + this.getName();
};
```
**[⬆ back to top](#table-of-contents)**
## Events
- When attaching data payloads to events (whether DOM events or something more proprietary like Backbone events), pass 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:
```js
// bad
$(this).trigger('listingUpdated', listing.id);
...
$(this).on('listingUpdated', function(e, listingId) {
// do something with listingId
});
```
prefer:
```js
// good
$(this).trigger('listingUpdated', { listingId : listing.id });
...
$(this).on('listingUpdated', function(e, data) {
// do something with data.listingId
});
```
**[⬆ back to top](#table-of-contents)**
## Modules
- The module should start with a `!`. This ensures that if a malformed module forgets to include a final semicolon there aren't errors in production when the scripts get concatenated. [Explanation](https://github.com/airbnb/javascript/issues/44#issuecomment-13063933)
- The file should be named with camelCase, live in a folder with the same name, and match the name of the single export.
- Add a method called `noConflict()` that sets the exported module to the previous version and returns this one.
- Always declare `'use strict';` at the top of the module.
```javascript
// fancyInput/fancyInput.js
!function(global) {
'use strict';
var previousFancyInput = global.FancyInput;
function FancyInput(options) {
this.options = options || {};
}
FancyInput.noConflict = function noConflict() {
global.FancyInput = previousFancyInput;
return FancyInput;
};
global.FancyInput = FancyInput;
}(this);
```
**[⬆ back to top](#table-of-contents)**
## jQuery
- Prefix jQuery object variables with a `$`.
```javascript
// bad
var sidebar = $('.sidebar');
// good
var $sidebar = $('.sidebar');
```
- Cache jQuery lookups.
```javascript
// bad
function setSidebar() {
$('.sidebar').hide();
// ...stuff...
$('.sidebar').css({
'background-color': 'pink'
});
}
// good
function setSidebar() {
var $sidebar = $('.sidebar');
$sidebar.hide();
// ...stuff...
$sidebar.css({
'background-color': 'pink'
});
}
```
- For DOM queries use Cascading `$('.sidebar ul')` or parent > child `$('.sidebar > ul')`. [jsPerf](http://jsperf.com/jquery-find-vs-context-sel/16)
- Use `find` with scoped jQuery object queries.
```javascript
// bad
$('ul', '.sidebar').hide();
// bad
$('.sidebar').find('ul').hide();
// good
$('.sidebar ul').hide();
// good
$('.sidebar > ul').hide();
// good
$sidebar.find('ul').hide();
```
**[⬆ back to top](#table-of-contents)**
## ECMAScript 5 Compatibility
- Refer to [Kangax](https://twitter.com/kangax/)'s ES5 [compatibility table](http://kangax.github.com/es5-compat-table/).
**[⬆ back to top](#table-of-contents)**
## Testing
- **Yup.**
```javascript
function() {
return true;
}
```
**[⬆ back to top](#table-of-contents)**
## Performance
- [On Layout & Web Performance](http://kellegous.com/j/2013/01/26/layout-performance/)
- [String vs Array Concat](http://jsperf.com/string-vs-array-concat/2)
- [Try/Catch Cost In a Loop](http://jsperf.com/try-catch-in-loop-cost)
- [Bang Function](http://jsperf.com/bang-function)
- [jQuery Find vs Context, Selector](http://jsperf.com/jquery-find-vs-context-sel/13)
- [innerHTML vs textContent for script text](http://jsperf.com/innerhtml-vs-textcontent-for-script-text)
- [Long String Concatenation](http://jsperf.com/ya-string-concat)
- Loading...
**[⬆ back to top](#table-of-contents)**
## Resources
**Read This**
- [Annotated ECMAScript 5.1](http://es5.github.com/)
**Tools**
- Code Style Linters
+ [JSHint](http://www.jshint.com/) - [Airbnb Style .jshintrc](https://github.com/airbnb/javascript/blob/master/linters/jshintrc)
+ [JSCS](https://github.com/jscs-dev/node-jscs) - [Airbnb Style Preset](https://github.com/jscs-dev/node-jscs/blob/master/presets/airbnb.json)
**Other Styleguides**
- [Google JavaScript Style Guide](http://google-styleguide.googlecode.com/svn/trunk/javascriptguide.xml)
- [jQuery Core Style Guidelines](http://docs.jquery.com/JQuery_Core_Style_Guidelines)
- [Principles of Writing Consistent, Idiomatic JavaScript](https://github.com/rwldrn/idiomatic.js/)
- [JavaScript Standard Style](https://github.com/feross/standard)
**Other Styles**
- [Naming this in nested functions](https://gist.github.com/4135065) - Christian Johansen
- [Conditional Callbacks](https://github.com/airbnb/javascript/issues/52) - Ross Allen
- [Popular JavaScript Coding Conventions on Github](http://sideeffect.kr/popularconvention/#javascript) - JeongHoon Byun
- [Multiple var statements in JavaScript, not superfluous](http://benalman.com/news/2012/05/multiple-var-statements-javascript/) - Ben Alman
**Further Reading**
- [Understanding JavaScript Closures](http://javascriptweblog.wordpress.com/2010/10/25/understanding-javascript-closures/) - Angus Croll
- [Basic JavaScript for the impatient programmer](http://www.2ality.com/2013/06/basic-javascript.html) - Dr. Axel Rauschmayer
- [You Might Not Need jQuery](http://youmightnotneedjquery.com/) - Zack Bloom & Adam Schwartz
- [ES6 Features](https://github.com/lukehoban/es6features) - Luke Hoban
- [Frontend Guidelines](https://github.com/bendc/frontend-guidelines) - Benjamin De Cock
**Books**
- [JavaScript: The Good Parts](http://www.amazon.com/JavaScript-Good-Parts-Douglas-Crockford/dp/0596517742) - Douglas Crockford
- [JavaScript Patterns](http://www.amazon.com/JavaScript-Patterns-Stoyan-Stefanov/dp/0596806752) - Stoyan Stefanov
- [Pro JavaScript Design Patterns](http://www.amazon.com/JavaScript-Design-Patterns-Recipes-Problem-Solution/dp/159059908X) - Ross Harmes and Dustin Diaz
- [High Performance Web Sites: Essential Knowledge for Front-End Engineers](http://www.amazon.com/High-Performance-Web-Sites-Essential/dp/0596529309) - Steve Souders
- [Maintainable JavaScript](http://www.amazon.com/Maintainable-JavaScript-Nicholas-C-Zakas/dp/1449327680) - Nicholas C. Zakas
- [JavaScript Web Applications](http://www.amazon.com/JavaScript-Web-Applications-Alex-MacCaw/dp/144930351X) - Alex MacCaw
- [Pro JavaScript Techniques](http://www.amazon.com/Pro-JavaScript-Techniques-John-Resig/dp/1590597273) - John Resig
- [Smashing Node.js: JavaScript Everywhere](http://www.amazon.com/Smashing-Node-js-JavaScript-Everywhere-Magazine/dp/1119962595) - Guillermo Rauch
- [Secrets of the JavaScript Ninja](http://www.amazon.com/Secrets-JavaScript-Ninja-John-Resig/dp/193398869X) - John Resig and Bear Bibeault
- [Human JavaScript](http://humanjavascript.com/) - Henrik Joreteg
- [Superhero.js](http://superherojs.com/) - Kim Joar Bekkelund, Mads Mobæk, & Olav Bjorkoy
- [JSBooks](http://jsbooks.revolunet.com/) - Julien Bouquillon
- [Third Party JavaScript](http://manning.com/vinegar/) - Ben Vinegar and Anton Kovalyov
- [Effective JavaScript: 68 Specific Ways to Harness the Power of JavaScript](http://amzn.com/0321812182) - David Herman
- [Eloquent JavaScript](http://eloquentjavascript.net) - Marijn Haverbeke
- [You Don't Know JS](https://github.com/getify/You-Dont-Know-JS) - Kyle Simpson
**Blogs**
- [DailyJS](http://dailyjs.com/)
- [JavaScript Weekly](http://javascriptweekly.com/)
- [JavaScript, JavaScript...](http://javascriptweblog.wordpress.com/)
- [Bocoup Weblog](http://weblog.bocoup.com/)
- [Adequately Good](http://www.adequatelygood.com/)
- [NCZOnline](http://www.nczonline.net/)
- [Perfection Kills](http://perfectionkills.com/)
- [Ben Alman](http://benalman.com/)
- [Dmitry Baranovskiy](http://dmitry.baranovskiy.com/)
- [Dustin Diaz](http://dustindiaz.com/)
- [nettuts](http://net.tutsplus.com/?s=javascript)
**Podcasts**
- [JavaScript Jabber](http://devchat.tv/js-jabber/)
**[⬆ back to top](#table-of-contents)**
## In the Wild
This is a list of organizations that are using this style guide. Send us a pull request or open an issue and we'll add you to the list.
- **Aan Zee**: [AanZee/javascript](https://github.com/AanZee/javascript)
- **Adult Swim**: [adult-swim/javascript](https://github.com/adult-swim/javascript)
- **Airbnb**: [airbnb/javascript](https://github.com/airbnb/javascript)
- **American Insitutes for Research**: [AIRAST/javascript](https://github.com/AIRAST/javascript)
- **Apartmint**: [apartmint/javascript](https://github.com/apartmint/javascript)
- **Avalara**: [avalara/javascript](https://github.com/avalara/javascript)
- **Compass Learning**: [compasslearning/javascript-style-guide](https://github.com/compasslearning/javascript-style-guide)
- **DailyMotion**: [dailymotion/javascript](https://github.com/dailymotion/javascript)
- **Digitpaint** [digitpaint/javascript](https://github.com/digitpaint/javascript)
- **Evernote**: [evernote/javascript-style-guide](https://github.com/evernote/javascript-style-guide)
- **ExactTarget**: [ExactTarget/javascript](https://github.com/ExactTarget/javascript)
- **Gawker Media**: [gawkermedia/javascript](https://github.com/gawkermedia/javascript)
- **GeneralElectric**: [GeneralElectric/javascript](https://github.com/GeneralElectric/javascript)
- **GoodData**: [gooddata/gdc-js-style](https://github.com/gooddata/gdc-js-style)
- **Grooveshark**: [grooveshark/javascript](https://github.com/grooveshark/javascript)
- **How About We**: [howaboutwe/javascript](https://github.com/howaboutwe/javascript)
- **InfoJobs**: [InfoJobs/JavaScript-Style-Guide](https://github.com/InfoJobs/JavaScript-Style-Guide)
- **Intent Media**: [intentmedia/javascript](https://github.com/intentmedia/javascript)
- **Jam3**: [Jam3/Javascript-Code-Conventions](https://github.com/Jam3/Javascript-Code-Conventions)
- **Kinetica Solutions**: [kinetica/javascript](https://github.com/kinetica/javascript)
- **Mighty Spring**: [mightyspring/javascript](https://github.com/mightyspring/javascript)
- **MinnPost**: [MinnPost/javascript](https://github.com/MinnPost/javascript)
- **ModCloth**: [modcloth/javascript](https://github.com/modcloth/javascript)
- **Money Advice Service**: [moneyadviceservice/javascript](https://github.com/moneyadviceservice/javascript)
- **Muber**: [muber/javascript](https://github.com/muber/javascript)
- **National Geographic**: [natgeo/javascript](https://github.com/natgeo/javascript)
- **National Park Service**: [nationalparkservice/javascript](https://github.com/nationalparkservice/javascript)
- **Nimbl3**: [nimbl3/javascript](https://github.com/nimbl3/javascript)
- **Nordic Venture Family**: [CodeDistillery/javascript](https://github.com/CodeDistillery/javascript)
- **Orion Health**: [orionhealth/javascript](https://github.com/orionhealth/javascript)
- **Peerby**: [Peerby/javascript](https://github.com/Peerby/javascript)
- **Razorfish**: [razorfish/javascript-style-guide](https://github.com/razorfish/javascript-style-guide)
- **reddit**: [reddit/styleguide/javascript](https://github.com/reddit/styleguide/tree/master/javascript)
- **REI**: [reidev/js-style-guide](https://github.com/reidev/js-style-guide)
- **Ripple**: [ripple/javascript-style-guide](https://github.com/ripple/javascript-style-guide)
- **SeekingAlpha**: [seekingalpha/javascript-style-guide](https://github.com/seekingalpha/javascript-style-guide)
- **Shutterfly**: [shutterfly/javascript](https://github.com/shutterfly/javascript)
- **StudentSphere**: [studentsphere/javascript](https://github.com/studentsphere/javascript)
- **Target**: [target/javascript](https://github.com/target/javascript)
- **TheLadders**: [TheLadders/javascript](https://github.com/TheLadders/javascript)
- **T4R Technology**: [T4R-Technology/javascript](https://github.com/T4R-Technology/javascript)
- **Userify**: [userify/javascript](https://github.com/userify/javascript)
- **VoxFeed**: [VoxFeed/javascript-style-guide](https://github.com/VoxFeed/javascript-style-guide)
- **Weggo**: [Weggo/javascript](https://github.com/Weggo/javascript)
- **Zillow**: [zillow/javascript](https://github.com/zillow/javascript)
- **ZocDoc**: [ZocDoc/javascript](https://github.com/ZocDoc/javascript)
## Translation
This style guide is also available in other languages:
-  **German**: [timofurrer/javascript-style-guide](https://github.com/timofurrer/javascript-style-guide)
-  **Japanese**: [mitsuruog/javacript-style-guide](https://github.com/mitsuruog/javacript-style-guide)
-  **Brazilian Portuguese**: [armoucar/javascript-style-guide](https://github.com/armoucar/javascript-style-guide)
-  **Chinese(Traditional)**: [jigsawye/javascript](https://github.com/jigsawye/javascript)
-  **Chinese(Simplified)**: [adamlu/javascript-style-guide](https://github.com/adamlu/javascript-style-guide)
-  **Spanish**: [paolocarrasco/javascript-style-guide](https://github.com/paolocarrasco/javascript-style-guide)
-  **Korean**: [tipjs/javascript-style-guide](https://github.com/tipjs/javascript-style-guide)
-  **French**: [nmussy/javascript-style-guide](https://github.com/nmussy/javascript-style-guide)
-  **Russian**: [uprock/javascript](https://github.com/uprock/javascript)
-  **Bulgarian**: [borislavvv/javascript](https://github.com/borislavvv/javascript)
-  **Catalan**: [fpmweb/javascript-style-guide](https://github.com/fpmweb/javascript-style-guide)
-  **Polish**: [mjurczyk/javascript](https://github.com/mjurczyk/javascript)
## The JavaScript Style Guide Guide
- [Reference](https://github.com/airbnb/javascript/wiki/The-JavaScript-Style-Guide-Guide)
## Chat With Us About JavaScript
- Find us on [gitter](https://gitter.im/airbnb/javascript).
## Contributors
- [View Contributors](https://github.com/airbnb/javascript/graphs/contributors)
## License
(The MIT License)
Copyright (c) 2014 Airbnb
Permission is hereby granted, free of charge, to any person obtaining
a copy of this software and associated documentation files (the
'Software'), to deal in the Software without restriction, including
without limitation the rights to use, copy, modify, merge, publish,
distribute, sublicense, and/or sell copies of the Software, and to
permit persons to whom the Software is furnished to do so, subject to
the following conditions:
The above copyright notice and this permission notice shall be
included 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 OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
**[⬆ back to top](#table-of-contents)**
# };
