JavaScript returns undefined instead of value in recursive function [duplicate]

Question

I have a simple function to get value from nested arrays:

function getVal(arr){
  var el = arr[0];
  console.log(el);
  console.log(Array.isArray(el));
  if(Array.isArray(el)){
    getVal(el);
  }else{
    return el;
  }
}

And I get undefined all the time. Here is the console output:

getVal([["a"]]);
["a"]
true
"a"
false
undefined

As far as I understand, when el === "a" condition if(Array.isArray(el)) is satisfied and I get recursive call with getVal("a"), which gives undefined result. What's happening there? And why "a" is not returned?

Does this answer your question? Javascript: recursive function returns undefined for existing value or this one? or this one? or this one? — Ivar
– Ivar, Commented May 30, 2020 at 19:45

Shubham Khatri · Accepted Answer · 2020-05-30 19:42:47Z

4

You haven't return the value from the recursive function call when Array.isArray(el) is true. Return it like return getVal(el);

function getVal(arr){
  var el = arr[0];
  if(Array.isArray(el)){
    return getVal(el);
  }else{
    return el;
  }
}

console.log(getVal([["a"]]));

answered May 30, 2020 at 19:42

Shubham Khatri

284k58 gold badges431 silver badges411 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Dmitry Reutov · Accepted Answer · 2020-05-30 19:42:01Z

1

replace

getVal(el);

with

return getVal(el);

answered May 30, 2020 at 19:42

Dmitry Reutov

3,0321 gold badge9 silver badges22 bronze badges

1 Comment

anton latsapneu Over a year ago

Thanks, that worked!

Collectives™ on Stack Overflow

JavaScript returns undefined instead of value in recursive function [duplicate]

2 Answers 2

Comments

1 Comment

Linked

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

1 Comment

Linked

Related