var arr=["12",323,"ab","dss",313];
        var obj={"age":18,
                 "name":"sun",
                 "addr":"shanghai"
        };//其实对象，直接obj["mail"]==undefined就可以判断是否存在，主要判断数组
        console.log(indexOf("sun",obj));
        console.log(indexOf("abc",arr));
        function indexOf(str,obj){
            var num=0;
            for(var a in obj){
               if(str===obj[a]){
                   num=1;
                   break;
               }else{
                   num=-1;
               }
            }
            return num;
        }

var arr = new Array("jayc","yaoming","kobe");
var name = "yaoming";
if(!Array.indexOf){
Array.protoType.indexOf = function(Object){
for(var i = 0;i<this.length;i++){
if(this[i] == Object){
return i;
}
}
return -1;
}

var searchId = arr.indexOf(name);
alert(searchId);
}