JS中如何更加深度的复制对象

　　　　　　　　　var json = {a:6,b:4,c:[1,2,3]};

		var json2 = clone(arr);

		console.log(json2[‘b‘]);   //4
		
		function clone(obj){
				var oNew = new obj.constructor(obj.valueOf());
				if(obj.constructor == Object){
						for(var i in obj){
								oNew[i] = obj[i];
								if(typeof(oNew[i]) == ‘object‘){
										clone(oNew[i]);
								}
						}
				}
				return oNew;
		}