mix to javascript Object

mix.js

function _mix(sObj, nObj) {
  var obj_s, obj_n, i;
	if (sObj instanceof Object && nObj instanceof Object) {
		for (i in nObj) {
			if ((obj_s = sObj[i]) !== (obj_n = nObj[i])) {//避免循环 Avoid Circular
				sObj[i] = _mix(sObj[i], nObj[i]);
			}
		}
		return sObj;
	} else {
		return nObj;
	}
};
var a = {
	a: 'a'
}
var b = {
	b: 'b',
	d:a
}
a.c = b;
console.log(_mix(a, b))