Copy or merge a JavaScript object

copy-or-merge.js

obj = {'a':'b'};
obj2 = {'x':'y'};
var copy = JSON.parse(JSON.stringify(obj)); // Really fast! - copies original obj

copy['c'] = 'd';

console.log(obj); // Outputs: {'a':'b'}
console.log(copy); // Outputs: {'a':'b', 'c':'d'}

var merge = $.extend(true, obj, obj2); // Uses jQuery - changes original obj

console.log(obj);  // Outputs: {'a':'b', 'x':'y'}
console.log(merge);  // Outputs: {'a':'b', 'x':'y'}

// Use $.clone for DOM objects, this is just for JavaScript objects!

function merge() {
	var dst = arguments[0],
		src, p, args = [].splice.call(arguments, 0);

	while (args.length > 0) {
		src = args.splice(0, 1)[0];
		if (toString.call(src) == '[object Object]') {
			for (p in src) {
				if (src.hasOwnProperty(p)) {
					if (toString.call(src[p]) == '[object Object]') {
						dst[p] = merge(dst[p] || {}, src[p]);
					} else {
						dst[p] = src[p];
					}
				}
			}
		}
	}

	return dst;
}

// Uses plain JavaScript and works like the jQuery API
// For further info see this jsbin here: http://jsbin.com/sapoli/4/edit