如何在 JavaScript 中获取两个数组之间的差异? [英] How to get the difference between two arrays in JavaScript?

问题描述

有没有办法在 JavaScript 中返回两个数组之间的差异?

Is there a way to return the difference between two arrays in JavaScript?

例如:

var a1 = ['a', 'b'];
var a2 = ['a', 'b', 'c', 'd'];

// need ["c", "d"]

推荐答案

这个答案是 2009 年写的，所以有点过时了，对于理解问题也很有教育意义.我今天使用的最佳解决方案是

This answer was written in 2009, so it is a bit outdated, also it's rather educational for understanding the problem. Best solution I'd use today would be

let difference = arr1.filter(x => !arr2.includes(x));

(此处感谢其他作者)

我假设您正在比较一个普通数组.如果没有，您需要将 for 循环更改为 for .. in 循环.

I assume you are comparing a normal array. If not, you need to change the for loop to a for .. in loop.

function arr_diff (a1, a2) {

    var a = [], diff = [];

    for (var i = 0; i < a1.length; i++) {
        a[a1[i]] = true;
    }

    for (var i = 0; i < a2.length; i++) {
        if (a[a2[i]]) {
            delete a[a2[i]];
        } else {
            a[a2[i]] = true;
        }
    }

    for (var k in a) {
        diff.push(k);
    }

    return diff;
}

console.log(arr_diff(['a', 'b'], ['a', 'b', 'c', 'd']));
console.log(arr_diff("abcd", "abcde"));
console.log(arr_diff("zxc", "zxc"));

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