js 数组去重

//数组去重
        function delRepeat(arr){
            var len = arr.length;
            while(len){
                var last = arr[len-1];
                var index = arr.indexOf(last);
                if(index != -1 && index < (len-1)){
                    console.log(last);
                    arr.splice(len-1,1);
                }
                len--;
            }
            return arr;
        }