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?

• nickf: NULL is the same as null - you don't need to compare against it twice.
• sikas: @nickf: ok, why is giving me all the values even if I don`t type in any!
• josh.trow: 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.
• sikas: @josh.trow: how can I accomplish this?
• sjngm: you can shorten the if() to if (overheads[i].value)

Answer 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!

• sikas: if Im using floats, shall I use parseFloat` instead of parseInt??
• nickf: @sikas Yep. It would work the same (but you know, with floats). I only used parseInt because it's used in the OP.