How to get sum of array with "for" loop

Question

I'm a total newbie in JavaScript. I'm trying to learn it using programming experience in Python...

Let's say there is an array of integers [2,3,4,5]. I want to get sum of all items in it with for loop. In Python this gonna looks like

list_sum = 0
for i in [2,3,4,5]:
    list_sum += i

Result is 14

But if I try same in JavaScript:

var listSum = 0;
for (i in [2,3,4,5])
{
    listSum += i;
}

This will return 00123. Seems that item indexes concatenated in a string with initial listSum value. How to make code works as intended and to get sum of all array items as integer?

`for-in` loop is not for iterating `array`..And yes, those are indexes("`keys`") — Rayon, May 04 '16 at 08:45
`var listSum = 0; var input=[2,3,4,5]; for (var i in input) { listSum += input[i]; } console.log(listSum);` — Rayon, May 04 '16 at 08:46

score 0 · Accepted Answer · answered May 04 '16 at 08:46

0

You are doing wrong for loop syntax. check this : https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Statements/for

var listSum = 0;
var arr =  [2,3,4,5];
for (i=0;i<arr.length ; i++)
{
    listSum += arr[i];
}
document.write(listSum);

answered May 04 '16 at 08:46

Niklesh Raut

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this works. By the way `for (i in arr)` works also – Andersson May 04 '16 at 09:11

How to get sum of array with "for" loop

1 Answers1