jQuery extend

http://api.jquery.com/jquery.extend/

HTML

<p>http://api.jquery.com/jquery.extend/</p>
<div id="log"></div>

JavaScript

/* our code is like

	Document.prototype = jQuery.extend(Document.prototype, {

		getKeyString : function() {
			return this._mEntity.getKeyString(this._mEntity);
		},
*/

var normalcat = {
    size : "small",
    color: "black"
};

var supercat = {
    color: "red",
    superpower: "fly"
};

console.log("normalcat before", normalcat);

// !!! take care!!! normalcat will be changed!!!
var mixedcat = $.extend( normalcat, supercat );
console.log('mixedcatmixedcat',mixedcat);

console.log("normalcat after", normalcat);
console.log("supercat", supercat);
console.log("mixedcat", mixedcat);