Ortus JavaScript Style Guide(){

This guide was re-purposed for the Ortus Solutions team from the original author Airbnb (https://github.com/airbnb/javascript)

Types
Objects
Arrays
Strings
Functions
Properties
Variables
Hoisting
Conditional Expressions & Equality
Blocks
Comments
Whitespace
Leading Commas
Semicolons
Type Casting & Coercion
Naming Conventions
Accessors
Constructors
Events
jQuery
ES5 Compatibility
Performance
Resources
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

Please make note of the spacing and alignments.

[⬆]

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
};

Please make note of the spacing and alignments.

[⬆]

Arrays

Use the literal syntax for array creation

// bad
var items = new Array();

// good
var items = [ 1, 2, 3 ];

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,
    itemsCopy = [],
    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 );
    ...
}

Please note spacing when declaring arrays.

[⬆]

Functions

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 block as 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
if( currentUser ){
	var test = function test(){
		console.log( 'Yup.' );
	};
}

Never name a parameter arguments, this will take precedence 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...
}

Please make note of the spacing requirements

If you have more than 4 arguments, then break them into separate lines for readability, alongside the whitespacing:

// bad
function nope( name, options, arguments, collection, index ){
  // ...stuff...
}

// good
function yup( 
    name, 
    options, 
    arguments,
    collection,
    index
){
  // ...stuff...
}

Always use JSDoc (http://en.wikipedia.org/wiki/JSDoc) style commenting on all functions including closures if necessary:

/**
* The hint of the function
* @constructor
* @deprecated
* @see Object
* 
* @name The name argument
* @options The options argument
* @test The Test argument
*
* @return String
*/
function nope( name, options, test ){
  // ...stuff...
}

Please note the space left between the method annotations and the argument annotations and the return annotations

[⬆]

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 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

[⬆]

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

[⬆]

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!

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.

// 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.

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();
};

[⬆]

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:

// bad
$(this).trigger('listingUpdated', listing.id);

...

$(this).on('listingUpdated', function(e, listingId){
  // do something with listingId
});

prefer:

// good
$( this ).trigger( 'listingUpdated', { listingId : listing.id } );

...

$( this ).on( 'listingUpdated', function( e, data ){
  // do something with data.listingId
});

[⬆]

jQuery

Prefix jQuery object variables with a $.

// bad
var sidebar = $('.sidebar');

// good
var $sidebar = $( '.sidebar' );

Cache jQuery lookups.

// 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
Use find with scoped jQuery object queries.

// 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' );

[⬆]

ECMAScript 6 Compatibility

Refer to Kangax's ES5 compatibility table
Refer to the new 2015 ECMAScript references https://babeljs.io/docs/learn-es2015/

[⬆]

Performance

[⬆]

Resources

Read This

Other Styleguides

Other Styles

Naming this in nested functions - Christian Johansen
Conditional Callbacks

Further Reading

Understanding JavaScript Closures - Angus Croll

Books

JavaScript: The Good Parts - Douglas Crockford
JavaScript Patterns - Stoyan Stefanov
Pro JavaScript Design Patterns - Ross Harmes and Dustin Diaz
High Performance Web Sites: Essential Knowledge for Front-End Engineers - Steve Souders
Maintainable JavaScript - Nicholas C. Zakas
JavaScript Web Applications - Alex MacCaw
Pro JavaScript Techniques - John Resig
Smashing Node.js: JavaScript Everywhere - Guillermo Rauch

Blogs

[⬆]

License

(The MIT License)

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.

[⬆]

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Ortus JavaScript Style Guide(){

Table of Contents

Types

Objects

Arrays

Strings

Functions

Properties

Variables

Hoisting

Conditional Expressions & Equality

Blocks

Comments

Whitespace

Leading Commas

Semicolons

Type Casting & Coercion

Naming Conventions

Accessors

Constructors

Events

jQuery

ECMAScript 6 Compatibility

Performance

Resources

License

};

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