js数组去掉重复的元素

<script>
    Array.prototype.uniq = function() {  
        var temp = {}, len = this.length;

        for(var i=0; i < len; i++)  {  
            if(typeof temp[this[i]] == "undefined") {
                temp[this[i]] = 1;
            }  
        }  
        this.length = 0;
        len = 0;
        for(var i in temp) {  
            this[len++] = i;
        }  
        return this;  
    }  
   
    var a = ["sss","aaa","sss",4,2,3,1,1,"sss","aaa","sss",4,2,3,1,1
        ,"sss","aaa","sss",4,2,3,1,1,"sss","aaa","sss",4,2,3,1,1
        ,"sss","aaa","sss",4,2,3,1,1,"sss","aaa","sss",4,2,3,1,1
        ,"sss","aaa","sss",4,2,3,1,1,"sss","aaa","sss",4,2,3,1,1];  
    var b = [2,3,5,7]; 
    //--------------------------时间测试开始-------------------------
    start = new Date().getTime(); 
    var c = a.concat(a).concat(b).concat(a).concat(b).concat(a)
         .concat(b).concat(a).concat(b).concat(a).concat(b)
         .concat(a).concat(b).concat(b).concat(a).concat(b).uniq(); 

    document.write(c + " 长度 " + c.length); 
    end = new Date().getTime();
    
        document.write(" 耗时：" + (end - start) + "ms")
    //--------------------------时间测试结束--------------------------
        //IE结果：sss,aaa,4,2,3,1,5,7 长度 8 耗时：15ms
        //FF结果：sss,aaa,4,2,3,1,5,7 长度 8 耗时：2ms
</script>