js常用的数组去重方法

给出以下数组

var arr1 = new Array('1','2','3','3','5','4','5','6','5','5','88');

实现对数组的去重

1、双重for循环去重

 1 Array.prototype.Duplicate = function() {
 2     let arr = this;
 3     for(let i = 0; i < arr.length-1; i++) {
 4     　　for (let j = i+1; j < arr.length; j++) {
 5         　　if (arr[i] == arr[j]) {
 6             　　arr.splice(j, 1);
 7             　　j--;  // 删除元素之后，需要将数组的长度也减1，否则无法去除掉后面相同的值.
 8         　　};
 9     　　};
10     };
11     return arr;
12 }

2、利用递归调用去重

Array.prototype.Duplicate = function() {
    let arr = this;
    arr.sort();
    function loop(index) {
        if (index > 1) {
            if (arr[index] == arr[index-1]) {
                arr.splice(index, 1);
            };
            loop(index-1);
        };
    };
    loop(arr.length-1);
    return arr;
}

3、利用对象去重

Array.prototype.Duplicate = function() {
    let arr = this;
    let obj = {}
    let arr2 = []
    for (let i = 0; i < arr.length; i++) {
        if (!obj[arr[i]]) {
            obj[arr[i]] = true;
            arr2.push(arr[i]);
        }
    };
    return arr2;
}

4、利用indexOf

Array.prototype.Duplicate = function() {
    let arr = this;
    let arr2 = []
    for (let i = 0; i < arr.length; i++) {
        if (arr2.indexOf(arr[i]) == -1) {
            arr2.push(arr[i]);
        }
    };
    return arr2;
}

5、利用es6 includes方法判断

Array.prototype.Duplicate = function() {
    let arr = this;
    let arr2 = [];
    for (let i = 0; i < arr.length; i++) {
        if (!arr2.includes(arr[i])) {
            arr2.push(arr[i]);
        }
    }
    return arr2
}

console.log(arr1.Duplicate().toString());

// 1,2,3,5,4,6,88

js常用的数组去重方法

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