在JavaScript中计算两个数组交集[duplicate]

Question

var arr1 = ["mike", "sue", "tom", "kathy", "henry"]; //arr1.length = 5
var arr2 = ["howey", "jim", "sue", "jennifer", "kathy", "hank", "alex"]; //arr2.length = 7

我如何找到两个数组共有的值？在这种情况下，应返回“sue”和“kathy”。

Answer 1

下面是基于array.prototype.filter的交集函数

function intersect(a, b) {
    var t;
    if (b.length > a.length) t = b, b = a, a = t; // indexOf to loop over shorter
    return a.filter(function (e) {
        return b.indexOf(e) > -1;
    });
}

var arr1 = ["mike", "sue", "tom", "kathy", "henry"];
    arr2 = ["howey", "jim", "sue", "jennifer", "kathy", "hank", "alex"];

intersect(arr1, arr2); // ["sue", "kathy"]

您可能还需要考虑以下事项

var arr1 = ['sue', 'sue', 'kathy'],
    arr2 = ['kathy', 'kathy', 'sue'];

上面现在给出了[“Sue”,“Sue”,“Kathy”]。如果你不想重复，你可以做一个进一步的筛选。这也将使结果标准化。即。

return a
    .filter(/* .. */) // same as before
    .filter(function (e, i, c) { // extra step to remove duplicates
        return c.indexOf(e) === i;
    });