Find element in array using recursion - javascript

Question

I'm trying to select Nth element from array using this function:

function nthArr(arr, index){
    if (index === 0)
        return arr[index];
    else nthArr(arr.slice(1), --index);
}

nthArr([1,2,3,4,5,6],3)

I would await that it returns 4, but instead I get 'undefined'.
How should I return correct value?

Ummm... but why? Doesn't arr[index] work for all indices anyway? — John Bupit
– John Bupit, Commented Sep 11, 2015 at 19:46

Mureinik · Accepted Answer · 2015-09-11 19:46:59Z

3

You are missing a return statement in the else branch.

if (index === 0)
    return arr[index];
else {
    return nthArr(arr.slice(1), --index); // Note the return
}

answered Sep 11, 2015 at 19:46

Mureinik

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1 Comment

exactly - my java habits :-)

rnevius · Accepted Answer · 2015-09-11 19:53:24Z

2

You're missing a return statement...But why not just simplify the whole thing?

function nthArr(arr, index){
  return arr[index];
}

var result = document.getElementById('result');
result.textContent = nthArr([1,2,3,4,5,6], 3);

<span id="result"></span>

answered Sep 11, 2015 at 19:53

rnevius

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yes this is simpler, but I needed it for traversing list object