javascript recursion and scope clarification

Question

Doing a simple recursive function that calls another function and the scope is off to where it works the first time correctly but the next times it always sets param to undefined.

function log(string){
    console.log(string)
}

function repeat(operation, num, param) {
    if (num <= 0) return
    operation(param)
    return repeat(operation, --num)
}

repeat(log, 5, "hello there")

What is "par"? That variable appears only once and is never declared or assigned a value. Anyway, the recursive call only passes two arguments, so... — nnnnnn
– nnnnnn, Commented Feb 7, 2016 at 1:31
Well, you're not passing any param argument during the recursive call, so yes, it will be undefined... try this return repeat(operation, --num, param) — Mister Epic
– Mister Epic, Commented Feb 7, 2016 at 1:31

ChiralMichael · Accepted Answer · 2016-02-07 01:36:40Z

3

You are not passing the "param" parameter to the recursive calls.

function log(string){
    console.log(string)
}

function repeat(operation, num, param) {
    if (num <= 0) return
    operation(param)
    return repeat(operation, --num, param)
}

repeat(log, 5, "hello there")

should fix it.

answered Feb 7, 2016 at 1:36

ChiralMichael

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Comments

Gavriel · Accepted Answer · 2016-02-07 01:31:34Z

2

Fix your variable name:

par => param

operation(param)

answered Feb 7, 2016 at 1:31

Gavriel

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Comments

manonthemat · Accepted Answer · 2016-02-07 01:35:02Z

1

Are you sure you just didn't want to do this?

function log(string) {
    console.log(string);
}

function repeat(operation, num, param) {
    if (num <= 0) return;
    operation(param);
    return repeat(operation, --num, param);
}

repeat(log, 5, "hello there")

answered Feb 7, 2016 at 1:35

manonthemat

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Comments

Zelter Ady · Accepted Answer · 2016-02-07 01:39:13Z

1

The working code is:

function log(string){
    console.log(string)
}

function repeat(operation, num, param) {
    if (num <= 0) return
    operation(param)
    return repeat(operation, --num, param)
}

repeat(log, 5, "hello there")

When you call the repeat recursively you should provide the 3rd argument - param

diff: return repeat(operation, --num, param) on line 8

answered Feb 7, 2016 at 1:39

Zelter Ady

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