Javascript -> how to recursively add an array of numbers?

Question

I can't seem to figure out what's wrong with this code -> keeps throwing a "Maximum call stack size exceeded" error.

function arrayIntSum(array) {
    if (array === []){
        return 0;
    }
    else return array.shift() + arrayIntSum(array); 
}

Did you event tried debugging, change your if condition before ask here? -1 for lazyness — DontVoteMeDown
– DontVoteMeDown, Commented Jan 14, 2014 at 19:26
For informational purposes: array.reduce(function(sum, n) { return sum + n; }, 0); — cookie monster
– cookie monster, Commented Jan 14, 2014 at 19:30
@DontVoteMeDown, can you tell me how I should have approached debugging this problem? I've only been programming for 2 months and sometimes figuring out how to debug is as confusing for me as the algorithm itself. — i_made_that
– i_made_that, Commented Jan 14, 2014 at 19:42
@i_made_that sure! You can learn how to it in Chrome, Firefox or IE. But they're almost the same process between all browsers. — DontVoteMeDown
– DontVoteMeDown, Commented Jan 14, 2014 at 19:45

SLaks · Accepted Answer · 2014-01-14 19:25:02Z

9

Javascript objects are compared by reference.

[] creates a new array instance, which will will never equal your variable.

You want to check the length.

answered Jan 14, 2014 at 19:25

SLaks

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1 Comment

i_made_that Over a year ago

Sigh. yes. I shouldn't have missed that. Thanks for the explanation!

Mike Thomsen · Accepted Answer · 2014-01-14 19:25:58Z

2

function arrayIntSum(array) {
    if (array.length === 0){
        return 0;
    }
    else return array.shift() + arrayIntSum(array); 
}

answered Jan 14, 2014 at 19:25

Mike Thomsen

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Comments

The Mighty Programmer · Accepted Answer · 2014-01-14 19:41:07Z

1

You should check by this way : a.length==0

you compared a with [] , being a '[]' literal, it has different memory space. and a has different memory space. So they are never equal. so recursion cross its limit

edited Jan 14, 2014 at 19:41

answered Jan 14, 2014 at 19:28

The Mighty Programmer

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