JavaScript Style Guide
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README.md

README.md

Shutterfly JavaScript Style Guide() {

This guide is based on airbnb Guide with adaptations from the npm style guide

Table of Contents

  1. Types
  2. Objects
  3. Arrays
  4. Strings
  5. Functions
  6. Properties
  7. Variables
  8. Hoisting
  9. Conditional Expressions & Equality
  10. Blocks
  11. Comments
  12. Whitespace
  13. Comma First
  14. Semicolons
  15. Asynchronous
  16. Type Casting & Coercion
  17. Naming Conventions
  18. Accessors
  19. Constructors
  20. Errors
  21. Modules
  22. jQuery
  23. ES5 Compatability
  24. Testing
  25. Performance
  26. Resources
  27. Alternatives
  28. The JavaScript Style Guide Guide
  29. Contributors
  30. License

Types

  • Primitives: When you access a primitive type you work directly on its value

    • String
    • Number
    • Boolean
    • null
    • undefined
    var foo = 1,
        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

    • Object
    • Array
    • Function
    var foo = [1, 2],
        bar = foo;
    
    bar[0] = 9;
    
    console.log(foo[0], bar[0]); // => 9, 9

    [⬆]

Objects

  • Use the literal syntax for object creation.

    // bad
    var item = new Object();
    
    // good
    var item = {};
  • Don't use reserved words as keys.

    // bad
    var superman = {
        class: 'superhero',
        default: { clark: kent },
        private: true
    };
    
    // good
    var superman = {
        klass: 'superhero',
        defaults: { clark: kent },
        hidden: true
    };

    [⬆]

Arrays

  • Use the literal syntax for array creation

    // bad
    var items = new Array();
    
    // good
    var items = [];
  • For performance reasons use direct assignment over Array#push

    var len = items.length,
        itemsCopy = [],
        i;
    
    // bad
    for (i = 0; i < len; i++) {
        itemsCopy.push(items[i])
    }
    
    // good
    for (i = 0; i < len; i++) {
        itemsCopy[i] = items[i];
    }

    [⬆]

Strings

  • 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.

    // 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 programatically building up a string, use Array#join instead of string concatenation. Mostly for IE: jsPerf.

    var items,
        messages,
        length, 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] = messages[i].message;
      }
    
      return '<ul><li>' + items.join('</li><li>') + '</li></ul>';
    }

    [⬆]

Functions

  • Use named functions. They make stack traces a lot easier to read and they avoid problems with hoisting
  • Function expressions:
 // named function expression
 var named = function named() {
   return true;
 };

 // immediately-invoked function expression (IIFE)
 (function() {
   console.log('Welcome to the Internet. Please follow me.');
 })();

 // **avoid** anonymous function expression
 var anonymous = function() {
   return true;
 };
  • 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.

    // bad
    if (currentUser) {
      function test() {
        console.log('Nope.');
      }
    }
    
    // good
    if (currentUser) {
      var test = function test() {
        console.log('Yup.');
      };
    }
  • Never name a parameter arguments, this will take precendence over the arguments object that is given to every function scope.

    // bad
    function nope(name, options, arguments) {
      // ...stuff...
    }
    
    // good
    function yup(name, options, args) {
      // ...stuff...
    }

    [⬆]

Properties

  • 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');

    [⬆]

Variables

  • Always use var 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.

    // bad
    superPower = new SuperPower();
    
    // good
    var superPower = new SuperPower();
  • Use one var declaration for multiple variables and declare each variable on a newline.

    // bad
    var items = getItems();
    var goSportsTeam = true;
    var dragonball = 'z';
    
    // good
    var items = getItems(),
        goSportsTeam = true,
        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, items = getItems(),
        dragonball,
        goSportsTeam = true,
        len;
    
    // good
    var items = getItems(),
        goSportsTeam = true,
        dragonball,
        i, length;
  • 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;
    }

    [⬆]

Hoisting

  • 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 interpretor 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 expression 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

    [⬆]

Conditional Expressions & Equality

  • Use === and !== over == and !=.

  • Conditional expressions are evaluated using coercion with the ToBoolean 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 evalute 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

    [⬆]

Blocks

  • 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;
    }

    [⬆]

Comments

  • 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 emptyline 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;
    }

    [⬆]

Whitespace

  • Use soft tabs set to 4 spaces

    // bad
    function() {
    ∙∙var name;
    }
    
    // bad
    function() {
    ∙var name;
    }
    
    // good
    function() {
    ∙∙∙∙var name;
    }
  • Place 1 space before the leading brace.

    // 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'
    });
  • Do not place a space after a control statement

// bad if (bad) mojo ()

// good if(good) luck() ```

  • Do not have more than 1 blank line at the end of a file

    // bad
    (function(global) {
      // ...stuff...
    })(this);
    
    
    
    // good
    (function(global) {
      // ...stuff...
    })(this);
    
  • Use indentation when making long method chains.

// 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);
**[[⬆]](#TOC)**

Comma First

Yes.

  • If there is a list of things separated by commas, and it wraps across multiple lines, put the comma at the start of the next line, directly below the token that starts the list. Put the final token in the list on a line by itself.

    // bad
    var once,
        upon,
        aTime;
    
    // good
    var once
      , upon
      , aTime
    
    // bad
    var hero = {
      firstName: 'Bob',
      lastName: 'Parr',
      heroName: 'Mr. Incredible',
      superPower: 'strength'
    };
    
    // good
    var magicWords = [ "abracadabra"
                     , "gesundheit"
                     , "ventrilo"
                     ]
      , spells = { "fireball" : function () { setOnFire() }
                 , "water" : function () { putOut() }
                 }
      , a = 1
      , b = "abc"
      , etc
      , somethingElse

    results in:

    • easier to identify missing separaters (esp. in code reviews)

    [⬆]

Semicolons

Don't use them except in four situations:

  • for (;;) loops. They're actually required.

  • null loops like: while (something) ; (But you'd better have a good reason for doing that.)

  • case "foo": doSomething(); break

  • In front of a leading ( or [ at the start of the line. This prevents the expression from being interpreted as a function call or property access, respectively.

    // bad
    (function() {
      var name = 'Skywalker';
      return name;
    })();
    
    // good
    ;(x || y).doSomething()
    ;[a, b, c].forEach(doSomething)
    for (var i = 0; i < 10; i ++) {
      switch (state) {
        case "begin": start(); continue
        case "end": finish(); break
        default: throw new Error("unknown state")
      }
      end()
    }
    ;(function(window) {
        // do something
    })()

    [⬆]

Asynchronous

- The callback should always be the last argument in the list. Its first argument is the Error or null.
- Send the error message back as the first argument to the callback.

```javascript
// bad
function async(data, callback) {
    var result = doStuff()
    if(isError(result))
        throw new Error('I kill state and failed to inform')
}

// good
function async(data, callback) {
    var result = doStuff()
    if(isError(result))
        callback(result)
    else
        callback(null, result)
}
```

**[[⬆]](#TOC)**

Type Casting & Coercion

  • Perform type coercion at the beginning of the statement.

  • Strings:

    //  => 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.

  • 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.

    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);
    
    // 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;
  • Booleans:

    var age = 0;
    
    // bad
    var hasAge = new Boolean(age);
    
    // good
    var hasAge = Boolean(age);
    
    // good
    var hasAge = !!age;

    [⬆]

Naming Conventions

  • In general avoid single letter names. Be descriptive.
    // 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 = {};
  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';
  ```

- 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);
  };
  ```

  **[[⬆]](#TOC)**


## <a name='accessors'>Accessors</a>

- 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];
  };
  ```

  **[[⬆]](#TOC)**


## <a name='constructors'>Constructors</a>

- 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();
  };
  ```

  **[[⬆]](#TOC)**


## <a name='errors'>Errors</a>

- Never throw in an asynchronous method.
- always create a new Error object as it provides a call stack for debugging

**[[⬆]](#TOC)**


## <a name='modules'>Modules</a>

- 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.
- 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.
- 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) {
      options || (options = {});
    }

    FancyInput.noConflict = function noConflict() {
      global.FancyInput = previousFancyInput;
    };

    global.FancyInput = FancyInput;
  }(this);
  ```

  **[[⬆]](#TOC)**


## <a name='jquery'>jQuery</a>

- 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
  $('.sidebar', 'ul').hide();

  // bad
  $('.sidebar').find('ul').hide();

  // good
  $('.sidebar ul').hide();

  // good
  $('.sidebar > ul').hide();

  // good (slower)
  $sidebar.find('ul');

  // good (faster)
  $($sidebar[0]).find('ul');
  ```

  **[[⬆]](#TOC)**


## <a name='es5'>ECMAScript 5 Compatability</a>

- Refer to [Kangax](https://twitter.com/kangax/)'s ES5 [compatibility table](http://kangax.github.com/es5-compat-table/)

**[[⬆]](#TOC)**


## <a name='testing'>Testing</a>

- **Yes.**

A separate describe (object literal in the case of nodeunit) is used for each functional unit tested.  This keeps
beforeEach and afterEach relevant to the unit under test and helps to group tests.


  ```javascript
  function() {
    return true;
  }
  ```

  **[[⬆]](#TOC)**


## <a name='performance'>Performance</a>

- [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)
- Loading...

**[[⬆]](#TOC)**


## <a name='alternatives'>Alternatives</a>
This section highlights considerations when choosing an alternative style

- **comma-first**
  If your team chooses to not use comma-first then use of jslint and jshint is necessary to identify syntax errors as
  well as placing "use strict"; at the top of the functional scope to avoid global variable declarations.
  Before avoiding comma-first, consider [is there something to the
  crazy comma-first style](http://ajaxian.com/archives/is-there-something-to-the-crazy-comma-first-style)

  ``` javascript
  // ok
  var o = {
      a : "ape",
      b : "bat",
      c : "cat",
      d : "dog",
      e : "elf",
      f : "fly",
      g : "gnu",
      h : "hat",
      i : "ibu"
    },
    a = [
      [ "ape", "bat" ],
      [ "cat", "dog" ],
      [ "elf", "fly" ],
      [ "gnu", "hat" ],
      [ "ibu" ]
    ];

    // preferable
    var o =
        { a : "ape"
        , b : "bat"
        , c : "cat"
        , d : "dog"
        , e : "elf"
        , f : "fly"
        , g : "gnu"
        , h : "hat"
        , i : "ibu"
        }
      , a = [ ["ape", "bat"]
            , ["cat", "dog"]
            , ["elf", "fly"]
            , ["gnu", "hat"]
            , ["ibu"]
            ]
  ```

- **semi-colons**
  If your team does not want to rely on automatic semi-colon insertion (ASI) then it is necessary to use jslint and
  jshint to identify syntax errors and terminate function declarations with semi-colons

  ```javascript
  // bad
  function() {
      console.log(arguments.length);  // 1
  }

  (function() {
      console.log('I am an argument');
  })();

  // ok
  function() {
      console.log(argument.length); // 0
  };

  (function() {
      console.log('I am not an argument');
  })();

  // preferable
  function() {
      console.log(argument.length) // 0
  }

  ;(function() {
      console.log('I am not an argument');
  })()
  ```

  In most cases it's easier to remember (and identify) when a semi-colon is missing in front of a ( or [ at the
  beginning of a line.


## <a name='resources'>Resources</a>


**Read This**

- [Annotated ECMAScript 5.1](http://es5.github.com/)

**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/)

**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

**Blogs**

- [DailyJS](//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/)
- [net.tutsplus](http://net.tutsplus.com/?s=javascript)

**[[⬆]](#TOC)**

## <a name='guide-guide'>The JavaScript Style Guide Guide</a>

- [Reference](//github.com/airbnb/javascript/wiki/The-JavaScript-Style-Guide-Guide)

## <a name='authors'>Contributors</a>

- [View Contributors](https://github.com/airbnb/javascript/graphs/contributors)


## <a name='license'>License</a>

(The MIT License)

Copyright (c) 2012 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.

**[[⬆]](#TOC)**

# };