area51/lib/es6/object-assign.js

Experimental prototypes of alien things built in JavaScript. The bits may end up living in a different package.

"use strict";

if (!Object.assign) {

	/**
  * Assigns the values of the source(s) to the target object.
  * 
  * @example
  * 		var target = {property: "value"},
  *     		targetRef = Object.assign(target, {newProperty: "value2"});
  *
  *     	console.log(targetRef); // {property: "value", {newProperty: "value2"}};
  *
  *      // multiple sources
  *      //
  *	    // [{}, {}].reduce(Object.assign, target);
  *      // Object.assign(target, {}, {}, {});
  *
  * @param {Object} target The object that will values replaced. 
  * @param {Object} source* The source of values that will replace the values in the the target.
  * @return {Object} The target object after value assignment has occurred.
  */
	Object.assign = function (target, source) {
		/// <summary> Assigns the values of the source(s) to the target object. </summary>
		/// <param name="target" type="object">The object that will have values replaced. </param>
		/// <source name="source" type="object">The source of values that will replace the values in the target. </param>
		/// <return type="object">Returns the target object.</return>

		var to,
		    sourceList = [],
		    i = 1,
		    l = 0;

		to = Object(target);

		if (arguments.length > 1) {
			l = arguments.length;
			sourceList = new Array(l - 1);

			for (; i < l; i++) sourceList[i - 1] = arguments[i];
		}

		l = sourceList.length;

		var mapObject = function mapObject(i) {
			var from = Object(sourceList[i]),
			    keysArray = Object.getOwnPropertyNames(from),
			    len = keysArray.length,
			    nextIndex = 0;

			while (nextIndex < len) {
				var nextKey = keysArray[nextIndex.toString()];
				var desc = from[nextKey];

				if (desc !== undefined && desc) {
					to[nextKey] = desc;
				}

				nextIndex++;
			}
		};

		for (i = 0; i < l; i++) {
			/* jshint loopfunc: true */
			mapObject(i);
		}

		return to;
	};
}