add values to one variable with for loop totalSum Javascript

Question

I have some values that come randomized to an variable. Now i want to add every value to each other to get an total sum but the loop wont add them together.

The index variable work when i console log it. but not the total sum of a current value and the index value. Any tips ?

This is the loop // The indexValue is values I get from an array//

  var indexValue = index;  // Random number from 1 - 10
    var totalSum = 0;

   for(var x = 0; x <indexValue; x++){

   var currentValue = index[x];
   totalSum += currentValue;
    }

    console.log(totalSum);

What is index? What exactly does it mean if a variable "does not work"? — Felix Kling
– Felix Kling, Commented Feb 6, 2013 at 17:53
on your first line, were u intending to do "var indexValue = index.length" ? — Dogoku
– Dogoku, Commented Feb 6, 2013 at 17:56

War10ck · Accepted Answer · 2013-02-06 18:10:12Z

2

I'm assuming since you're referencing index[x] that index is an array. If so, you are assigning the wrong value to indexValue. Try this:

var indexValue = index.length;

What this does is assign the length of the array to the variable indexValue. Now the for loop will run from 0 to n where n is the length of the array.

This should get you the values you need.

Hope this helps.

EDIT:

Below is a link to a jsFiddle I created with your example and the code explained:

jsFiddle

var index = [1,2,3,4,5];  

var indexValue = index.length;  // It's imperative that this is an array
var totalSum = 0;

for(var x = 0; x <indexValue; x++){
    totalSum += index[x];
}

alert(totalSum);

The code above is a modified version of what you posted. The current value is not needed and has been removed. In this case, I created an array and stored the values in index. The length is computed, and the values are added together.

For the easy sake of testing, I changed console.log(totalSum); to alert(totalSum);. It will produce the same value just the same.

Just a reference note on console.log. Some browsers (mainly IE) who do not attach the debugger to the process automatically without a page refresh will through an error as console will be undefined. Here is a quick fix for that:

if(window.console && window.console.log) {
    console.log(totalSum);
}

This checks that (a) the console object is attached to the global window object and (b) that the log object of console is attached to the console object.

edited Feb 6, 2013 at 18:10

answered Feb 6, 2013 at 17:54

War10ck

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4 Comments

Dymond Over a year ago

It still gives me value = 0 ; but if I console.log the index, it shows me the current value. but totalSum 0

War10ck Over a year ago

@Dymond See the edit above. Are you sure index is an array? You're original comment // Random number from 1 - 10 leads me to believe that it is not.

Dymond Over a year ago

aaa ofcourse. now when you said it. Its actually an string array, that I put values in with an loop . and then i get the value with getElement.. but when there are back. its a singel value, and not an array. So what I have to do is save the values in an array, and then call them with your function.. thank you :) now i really need the noob badge here :)

War10ck Over a year ago

@Dymond Haha. Nah its all good buddy. I'm glad it's working for you. Good luck and happy coding! :)

Mike Corcoran · Accepted Answer · 2013-02-06 17:55:02Z

0

you probably want something like this:

var sum = 0;
for (var i=0; i < index.length; i++) {
    sum += index[i];
}
console.log(sum);

answered Feb 6, 2013 at 17:55

Mike Corcoran

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