javascript summing up array

Question

I`m trying to sum the values of the elements in an array using javascript, this is my script.

function sumAll()
{
    var totalOverheads = 0;
    var overheads = new Array();
    overheads = document.getElementsByName('overhead');
    for(i=0;i<overheads.length;i++)
        if(!isNaN(overheads[i].value) || overheads[i].value != null || overheads[i].value != "" || overheads[i].value != '' || overheads[i].value != NULL)
            alert(overheads[i].value);
            //totalOverheads = parseInt(totalOverheads) + parseInt(overheads[i].value);
    alert(totalOverheads);
}

for now, in the if condition inside the for loop, I`m displaying the value of the item in an alert, yet it`s not working correctly, it just displays all the items even if the item is not a number, how can I perform an operation if the input is only a number?

NULL is the same as null - you don't need to compare against it twice. — nickf
– nickf, Commented Dec 26, 2010 at 15:59
@nickf: ok, why is giving me all the values even if I don`t type in any! — sikas
– sikas, Commented Dec 26, 2010 at 16:01
getElementsByName returns an array of objects. you need an outer loop to loop through those and an inner to loop through the items in each array. — josh.trow
– josh.trow, Commented Dec 26, 2010 at 16:01

nickf · Accepted Answer · 2010-12-26 16:03:14Z

1

getElementsByName returns a NodeList. Not sure if that was the problem, but anyway:

var totalOverheads = 0;
var overheads = document.getElementsByName('overhead');
var n;
var i; // <<--- don't forget to initialise i
for (i = 0; i < overheads.length; ++i) {
    n = parseInt(overheads.item(i).value, 10);
    if (!isNaN(n)) {
        totalOverheads += n;
    }
}
alert(totalOverheads);

Also, please use brackets!

answered Dec 26, 2010 at 16:03

nickf

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2 Comments

sikas Over a year ago

if Im using floats, shall I use parseFloat` instead of parseInt??

nickf Over a year ago

@sikas Yep. It would work the same (but you know, with floats). I only used parseInt because it's used in the OP.

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