数组去重的几个方法

---

title: 数组去重的几个方法
date: 2017-11-11
tags: mac apache CGI

---

数据去重

    //1、排序去重
    var arr = [1, 4, 5, 6, 20, 3, 5, 7, 2, 3, 2, 1, 6, '1'];
    arr.sort(function(a, b) {
        return a - b;
    });
    console.log(arr);
    var result = [];  
    var len = arr.length;　
    for (var i = 0; i < len; i++) {     
        if (arr[i] !== arr[i + 1]) {     
            result.push(arr[i]);     
        }   
    }
    console.log(result);

    //2、不排序直接去重
    var arr2 = [1, 4, 5, 6, 20, 3, 5, 7, 2, 3, 2, 1, 6, '1'];

    function unique2(arr2) {
        var len2 = arr2.length;
        var result2 = [],
            falg;
        for (var i = 0; i < arr2.length; i++) {
            flag = false;
            for (var j = i + 1; j < arr2.length; j++) {
                if (arr2[i] === arr2[j]) {
                    //有相等
                    flag = true;
                    break;
                }
            }
            if (!flag) {
                result2.push(arr2[i]);
            }
        }

        return result2;
    }


    //3   第三种方式  利用hashTable
    function unique(arr) {
        var result = [],
            hash = {};
        for (var i = 0, elem;
            (elem = arr[i]) != null; i++) {
            if (!hash[elem]) {
                result.push(elem);
                hash[elem] = true;
            }
        }
        return result;
    }
    console.log("11");
    console.log(unique(arr2));

    var num1 = 100;
    console.log(~num1); //-101


    var num = 0;

    for (var i = 0; i < 10; i++) {
        for (var j = 0; j < 10; j++) {
            if (i == 5 && j == 5) {
                break;
            }
            num++;
        }
    }
    //alert(num);



    function add(num1, num2) {
        arguments[1] = 10;
        return arguments[0] + arguments[1];
    }

    var a = 5,
        b = 20;
    console.log(add(a, b));
    console.log(b);

个人感觉hash去重的效果较好