CODEWITHSUNDEEP
javascript
Timothy Pulliam
Timothy Pulliam

Reputation: 142

javascript function only returns undefined

The following javascript function only returns undefined

function digital_root(n) {
  var x = String(n).split('');
  if (x.length > 1) {
    sum = x.reduce((accumulator, value) => parseInt(value) + accumulator, 0);
    digital_root(sum);
  } else {
    console.log(x);
    return x;
  }
}

however it prints the correct value when run in node. So why does it return undefined?

> digital_root(12)
[ '3' ]
undefined

If I take the console.log(x) statement out, the function still returns undefined

> digital_root(12)
undefined

Upvotes: 1

Views: 58

Answers (2)

connexo
connexo

Reputation: 56720

The first time your function runs it goes into the if block, where it calls itself again with argument digital_root(3).

This "inner" call is processed first now, this time going into the else block, where the console.log(x) call happens and then return ['3'] explicitly returns that value to the outer function call, so that return value is not shown on the console.

After the inner call returned the value, the outer function terminates, because there's nothing left to do, so the outer function never returns anything.

Functions do have a default return value of undefined whenever there is not explicit return statement.

Upvotes: 1

Timothy Pulliam
Timothy Pulliam

Reputation: 142

I figured it out. I needed to include return for the recursive call.

The full code should look like this

function digital_root(n) {
  var x = String(n).split('');
  if (x.length > 1) {
    sum = x.reduce((accumulator, value) => parseInt(value) + accumulator, 0);
    return digital_root(sum);
  } else {
    console.log(x);
    return x;
  }
}

Upvotes: 0

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