function isObj(x){	
	var type = typeof x;
	return x !== null && (type === 'object' || type === 'function');
var hasOwnProperty = Object.prototype.hasOwnProperty;
var propIsEnumerable = Object.prototype.propertyIsEnumerable;
function toObject(val) {
	if (val === null || val === undefined) {
		throw new TypeError('Cannot convert undefined or null to object');
	return Object(val);
function assignKey(to, from, key) {
	var val = from[key];
	if (val === undefined || val === null) {
		return;
	if (hasOwnProperty.call(to, key)) {
		if (to[key] === undefined || to[key] === null) {
			throw new TypeError('Cannot convert undefined or null to object (' + key + ')');
	if (!hasOwnProperty.call(to, key) || !isObj(val)) {
		to[key] = val;
	} else {
		to[key] = assign(Object(to[key]), from[key]);
function assign(to, from) {
	if (to === from) {
		return to;
	from = Object(from);
	for (var key in from) {
		if (hasOwnProperty.call(from, key)) {
			assignKey(to, from, key);
	if (Object.getOwnPropertySymbols) {
		var symbols = Object.getOwnPropertySymbols(from);
		for (var i = 0; i < symbols.length; i++) {
			if (propIsEnumerable.call(from, symbols[i])) {
				assignKey(to, from, symbols[i]);
	return to;
function deepAssign(target) {
	target = toObject(target);
	for (var s = 1; s < arguments.length; s++) {
		assign(target, arguments[s]);
	return target;
deepAssign({a: {b: 0}}, {a: {b: 1, c: 2}}, {a: {c: 3}});
//=> {a: {b: 1, c: 3}}