Javascript Operators Issue working with Decimals

Question

I got everything almost where I want it. My only problem is that for some reason I can't get the bctf1 to add right. Say if bctf = 10, the result with the code would be 100.59 instead of 10.59. Say if bctf = 25, the result with the code would be $251.03 instead of 26.03.

// BUY TOTAL
<script type="text/javascript">
function buytot(){
var bctf = document.getElementById('buyctf').value;
if(bctf.charAt(0) == "0" || bctf.charAt(0) == "" || bctf.charAt(0) == " "){
bctf2 = "0.00";
} else {
pcbctf = bctf*.029;
pcplusc = pcbctf+.30;
bctf1 = bctf+pcplusc;
bctf2 = Math.round(bctf1*100)/100;
}
document.getElementById('buyctotal').innerHTML = bctf2;
}
</script>

Here's the HTML with JS -> http://jsfiddle.net/hhWDe/5/

This would be so much easier to help with if we could see your HTML. Could you post that? And, ideally, a JS Fiddle demo? — David Thomas
– David Thomas, Commented Dec 1, 2011 at 21:51

Diodeus - James MacFarlane · Accepted Answer · 2011-12-01 21:51:05Z

1

Force a data type on this:

var bctf = parseFloat(document.getElementById('buyctf').value);

answered Dec 1, 2011 at 21:51

Diodeus - James MacFarlane

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1 Comment

Diodeus - James MacFarlane Over a year ago

That's because the rest of your code is treating it as a string. It's a number now. i.e. bctf.charAt(0) == "0", expects a string. Adjust your code accordingly.

maerics · Accepted Answer · 2011-12-01 21:58:23Z

1

You need to convert the String values returned by the element value properties into numbers. Something like this:

var bctf = Number(document.getElementById('buyctf').value);
// OR
var bctf = parseFloat(document.getElementById('buyctf').value, 10);

Also, consider using the "toFixed" number method to get the ".00 decimal places for whole dollar amounts:

var oneDollar = 1;
oneDollar; // => 1
oneDollar.toFixed(2); // => "1.00"

answered Dec 1, 2011 at 21:58

maerics

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Comments

Jan · Accepted Answer · 2011-12-01 22:12:09Z

1

You can add "+" to convert a value to an integer (or float).

It will take any string and convert it, if the string cannot be converted, it will return NaN:

So your script would look like the following:

var bcft = +document.getElementByID('buyctf').value;

answered Dec 1, 2011 at 22:12

Jan

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Comments

yanike · Accepted Answer · 2011-12-01 22:58:03Z

0

Thank You all :) This is the working code. I add bctf0 = Number(document.getElementById('buyctf').value); after the else and everything worked fine.

// BUY TOTAL
function buytot(){
var bctf = document.getElementById('buyctf').value;
if(bctf.charAt(0) == "0" || bctf.charAt(0) == "" || bctf.charAt(0) == " "){ bctf2 = "0.00";
} else {
bctf0 = Number(document.getElementById('buyctf').value);
pcbctf = bctf0*.029;
pcplusc = pcbctf+.30;
bctf1 = bctf0+pcplusc;
bctf2 = Math.round(bctf1*100)/100;
}
document.getElementById('buyctotal').innerHTML = bctf2;
}

answered Dec 1, 2011 at 22:58

yanike

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