JavaScript数组的区别 [英] JavaScript array difference

问题描述

有没有办法返回在JavaScript中两个数组之间的区别？

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"]

任何意见很大AP preciated。

Any advice greatly appreciated.

推荐答案

我假设你是一个比较正常的数组。如果没有，您需要将的为的循环更改为的的。在的循环。

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;
};

有一个更好的解决方案，如果你不关心向后兼容性，使用过滤器。但尽管如此，这个解决方案有效，所以投票下来是不公平的。

A better solution, if you don't care about backward compatibility, is using filter. But still, this solution works, so voting it down is unfair.

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