javascript return of recursive function [duplicate]

Question

Hate to open a new question for an extension to the previous one:

function ctest() {
    this.iteration = 0;
    this.func1 = function() {
        var result = func2.call(this, "haha");
        alert(this.iteration + ":" + result);
    }
    var func2 = function(sWord) {
        this.iteration++;
        sWord = sWord + "lol";
        if ( this.iteration < 5 ) {
            func2.call(this, sWord);
        } else {
            return sWord;
        }
    }
}

this returns iteration = 5 but result UNDEFINED ? how is that possible ? i explicitly return sWord. It should have returned "hahalollollollollol" and just for doublecheck, if i alert(sWord) just before the return sWord it displays it correctly.

Does this answer your question? Recursive function returns undefined — ggorlen
– ggorlen, Commented Aug 17, 2021 at 21:25

Quentin · Accepted Answer · 2012-05-23 12:05:12Z

32

You have to return all the way up the stack:

func2.call(this, sWord);

should be:

return func2.call(this, sWord);

answered May 23, 2012 at 12:05

Quentin

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Comments

Rich O'Kelly · Accepted Answer · 2012-05-23 12:05:34Z

5

You need to return the result of the recursion, or else the method implicitly returns undefined. Try the following:

function ctest() {
this.iteration = 0;
  this.func1 = function() {
    var result = func2.call(this, "haha");
    alert(this.iteration + ":" + result);
  }
  var func2 = function(sWord) {
    this.iteration++;
    sWord = sWord + "lol";
    if ( this.iteration < 5 ) {
        return func2.call(this, sWord);
    } else {
        return sWord;
    }
  }
}

answered May 23, 2012 at 12:05

Rich O'Kelly

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Comments

alex · Accepted Answer · 2012-05-23 12:04:00Z

0

Your outer function doesn't have a return statement, so it returns undefined.

answered May 23, 2012 at 12:04

alex

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1 Comment

gre_gor Over a year ago

The outer function is supposed to be a class constructor. It doesn't need to return anything. OP is clearly calling func1.

Community · Accepted Answer · 2017-10-05 09:47:22Z

0

keep it simple :)

your code modified in JSFiddle

iteration = 0;
func1();

    function  func1() {
        var result = func2("haha");
        alert(iteration + ":" + result);
    }

    function func2 (sWord) {
        iteration++;

        sWord = sWord + "lol";
        if ( iteration < 5 ) {
            func2( sWord);
        } else {

            return sWord;
        }

    return sWord;
    }

edited Oct 5, 2017 at 9:47

CommunityBot

11 silver badge

answered May 23, 2012 at 12:17

shareef

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1 Comment

gre_gor Over a year ago

I am pretty sure ctest is supposed to be a class constructor. And you still didn't fix the actual problem.

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