递归函数的返回值是'undefined' [英] Return value of recursive function is 'undefined'

问题描述

每当我执行此代码片段时，返回前的console.log会返回值为20的20倍的数组。
但是console.log（Check（users，0,20））;只返回'undefined'。

Whenever I execute this snippet the console.log before return returns the array with 20 times the value 23. However console.log(Check(users, 0, 20)); returns only 'undefined'.

我做错了什么？

var users = [23, 23, 23, 23, 23, 23, 23, 23, 23, 23];
console.log(Check(users, 0, 20));

function Check(ids, counter, limit){
    ids.push(23);

    // Recursion
    if (counter+1 < limit){
        Check(ids, counter+1, limit);
    }
    else {
        console.log(ids);
        return ids;
    }
}

推荐答案

你忘了从进入recusrion的点返回结果。

You forgot to return a result from the point, where you entering recusrion.

var users = [23, 23, 23, 23, 23, 23, 23, 23, 23, 23];
console.log(Check(users, 0, 20));

function Check(ids, counter, limit){
    ids.push(23);

    // Recursion
    if (counter+1 < limit){
        return Check(ids, counter+1, limit); // return here!
    }
    else {
        console.log(ids);
        return ids;
    }
} 

但返回值似乎没用，导致'你的功能改变初始数组。

But return value seems useless, cause' your function altering initial array as well.

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