如何判断JavaScript 数组含有重复值

Javascript判断一个数组中是否有重复值的三种方法：

判断重复方法一，转为字符串 进行比较:

var ary = new Array("aaa","cc","dd","aaa");

var s = ary.join(",")+",";

for(var i=0;i<ary.length;i++) {

    if(s.replace(ary[i]+",","").indexOf(ary[i]+",")>-1) {

        alert("数组中有重复元素:" + ary[i]);

        break;

    }

}

判断重复方法二，数组排序，再比较相邻的值:

var ary = new Array("bbb","cc","dd","bbb");

var nary=ary.sort();

for(var i=0;i<ary.length;i++){

    if (nary[i]==nary[i+1]){

        alert("数组重复内容为:"+nary[i]);

    }

}

判断重复方法三，自定义函数方法判断重复:

function isRepeat(arr){

    var hash = {};

    for(var i in arr) {

        if(hash[arr[i]])

            return true;

        hash[arr[i]] = true;

     }

    return false;

}