jQuery extend for NodeJS / Object & Array Deep Copy for NodeJS

jquery.extend.js

/*
	jQuery.extend extracted from the jQuery source & optimised for NodeJS
	Twitter: @FGRibreau / fgribreau.com

	Usage: 
		var Extend = require('./Extend');


		// Extend
		var obj = Extend({opt1:true, opt2:true}, {opt1:false});

		// Deep Copy
		var clonedObject = Extend(true, {}, myObject);
		var clonedArray = Extend(true, [], ['a',['b','c',['d']]]);
*/
var toString = Object.prototype.toString,
	hasOwn = Object.prototype.hasOwnProperty,
	push = Array.prototype.push,
	slice = Array.prototype.slice,
	trim = String.prototype.trim,
	indexOf = Array.prototype.indexOf,

	// [[Class]] -> type pairs
	class2type = {};

// Populate the class2type map
"Boolean Number String Function Array Date RegExp Object".split(" ").forEach(function(name) {
	class2type[ "[object " + name + "]" ] = name.toLowerCase();
});

function type(obj){
	return obj == null ?
			String( obj ) :
			class2type[ toString.call(obj) ] || "object";
}

function isPlainObject( obj ) {
	if ( !obj || type(obj) !== "object") {
		return false;
	}

	// Not own constructor property must be Object
	if ( obj.constructor &&
		!hasOwn.call(obj, "constructor") &&
		!hasOwn.call(obj.constructor.prototype, "isPrototypeOf") ) {
		return false;
	}

	// Own properties are enumerated firstly, so to speed up,
	// if last one is own, then all properties are own.

	var key;
	for ( key in obj ) {}

	return key === undefined || hasOwn.call( obj, key );
}

module.exports = function extend(){
	var options, name, src, copy, copyIsArray, clone,
		target = arguments[0] || {},
		i = 1,
		length = arguments.length,
		deep = false;

	// Handle a deep copy situation
	if ( typeof target === "boolean" ) {
		deep = target;
		target = arguments[1] || {};
		// skip the boolean and the target
		i = 2;
	}

	// Handle case when target is a string or something (possible in deep copy)
	if ( typeof target !== "object" && type(target) !== "function") {
		target = {};
	}

	// extend jQuery itself if only one argument is passed
	if ( length === i ) {
		target = this;
		--i;
	}

	for ( ; i < length; i++ ) {
		// Only deal with non-null/undefined values
		if ( (options = arguments[ i ]) != null ) {
			// Extend the base object
			for ( name in options ) {
				src = target[ name ];
				copy = options[ name ];

				// Prevent never-ending loop
				if ( target === copy ) {
					continue;
				}

				// Recurse if we're merging plain objects or arrays
				if ( deep && copy && ( isPlainObject(copy) || (copyIsArray = type(copy) === "array") ) ) {
					if ( copyIsArray ) {
						copyIsArray = false;
						clone = src && type(src) === "array" ? src : [];

					} else {
						clone = src && isPlainObject(src) ? src : {};
					}

					// Never move original objects, clone them
					target[ name ] = extend( deep, clone, copy );

				// Don't bring in undefined values
				} else if ( copy !== undefined ) {
					target[ name ] = copy;
				}
			}
		}
	}

	// Return the modified object
	return target;
};