数组去重的两种方式

/*第一种方式
    var hash ={
     key :value,
     "hello":true,
     "node":true,
     "world":true
     };*/

    function unique() {
        var arr = ["hello","world","node","hello","node","node","node","hello","world","momo"];
        var result = [], hash = {};
        for (var i = 0, elem; (elem = arr[i]) != null; i++) {
            if (!hash[elem]) { // . []
                result.push(elem);
                hash[elem] = true;
            }
        }
        return result;
    }

    unique();

    console.timeEnd("tag1");


    console.time("tag2");

//第二种方法
    function quchong(){
        var arr = ["hello","world","node","hello","node","node","node","hello","world","momo"];
        var arr2 =[];
        for(var i=0;i<arr.length;i++){
            if(arr2.indexOf(arr[i]) <0){
                arr2.push(arr[i]);
            }
        }
        return arr2;
    }
    quchong();

    console.timeEnd("tag2");

    console.time("unique");
    console.timeEnd("unique");

    console.time("quchong");
    console.timeEnd("quchong")