<script>
 //----------------for用来遍历数组对象--
 var i,myArr = [1,2,3];
 for (var i = 0; i < myArr.length; i++) {
  console.log(i+":"+myArr[i]);
 };
 //---------for-in 用来遍历非数组对象
 var man ={hands:2,legs:2,heads:1};
 //为所有的对象添加clone方法，即给内置原型(object,Array,function)增加原型属性,该方法很强大，也很危险
 if(typeof Object.prototype.clone ==="undefined"){
  Object.prototype.clone = function(){}; 
 }
 //
 for(var i in man){
  if (man.hasOwnProperty(i)) { //filter,只输出man的私有属性
   console.log(i,":",man[i]);
  };
 }
 //输出结果为print hands:2,legs:2,heads:1
 for(var i in man) {//不使用过滤
  console.log(i,":",man[i]);
 } 
 //输出结果为
 //hands : 2 index.html:20
 //legs : 2 index.html:20
 //heads : 1 index.html:20
 //clone : function (){} 
 for(var i in man) {
  if(Object.prototype.hasOwnProperty.call(man,i)) { //过滤
   console.log(i,":",man[i]);
  }
 } //输出结果为print hands:2,legs:2,heads:1 </script>