递归函数的返回值为“未定义"

Return value of recursive function is #39;undefined#39;(递归函数的返回值为“未定义)

问题描述

每当我执行此代码段时，console.log 在 return 之前返回的数组是值 23 的 20 倍.但是 console.log(Check(users, 0, 20));仅返回未定义".

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

您忘记从输入 recursion 的位置返回结果.

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;
    }
} 

但是返回值似乎没用，因为你的函数也改变了初始数组.

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

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