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Fixed decimal fields

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JonR

JonR

Technical User
Feb 21, 2001
22
US
Please help!

I have a simple order form (code pasted below) and I am having trouble making the fields only allowing for 2 decimal places.

For instance, when I calculate 3 x .35 I get 1.049999999999999

Can anyone help, or please let me know what I'm doing wrong? I am a beginner at javascript and perhaps there is also a better way to calculate fields too.

Thanks very much!

Jon

--------------------

<html>
<head>
<title>Test Form</title>

<SCRIPT LANGUAGE=&quot;JavaScript&quot;>

<!-- Begin
function calcTotal(form){
StoreOrderForm.Total1.value = (eval(StoreOrderForm.Qty1.value) * eval(StoreOrderForm.Price1.value));

StoreOrderForm.Total2.value = (eval(StoreOrderForm.Qty2.value) * eval(StoreOrderForm.Price2.value));

StoreOrderForm.Subtotal.value = (eval(StoreOrderForm.Total1.value) + eval(StoreOrderForm.Total2.value));

}
// End -->
</script>

</head>
<body>

<form method=&quot;POST&quot; name=&quot;StoreOrderForm&quot; action=&quot;--WEBBOT-SELF--&quot;>
<!--webbot bot=&quot;SaveResults&quot;
U-File=&quot; S-Format=&quot;TEXT/CSV&quot;
S-Label-Fields=&quot;TRUE&quot; -->

Qty: <input type=&quot;text&quot; name=&quot;Qty1&quot; size=&quot;20&quot; onChange=&quot;calcTotal(this.form)&quot; value=&quot;0.00&quot;>
Price: <input type=&quot;text&quot; name=&quot;Price1&quot; size=&quot;20&quot; onChange=&quot;calcTotal(this.form)&quot; value=&quot;0.00&quot;>
Total: <input type=&quot;text&quot; name=&quot;Total1&quot; size=&quot;20&quot; value=&quot;0.00&quot; readonly><br>

Qty: <input type=&quot;text&quot; name=&quot;Qty2&quot; size=&quot;20&quot; onChange=&quot;calcTotal(this.form)&quot; value=&quot;0.00&quot;>
Price: <input type=&quot;text&quot; name=&quot;Price2&quot; size=&quot;20&quot; onChange=&quot;calcTotal(this.form)&quot; value=&quot;0.00&quot;>
Total: <input type=&quot;text&quot; name=&quot;Total2&quot; size=&quot;20&quot; value=&quot;0.00&quot; readonly>

<p><b>Total: </b> <input type=&quot;text&quot; name=&quot;Subtotal&quot; size=&quot;20&quot; value=&quot;0.00&quot; readonly></p>

<p><input type=&quot;submit&quot; value=&quot;Submit&quot; name=&quot;B1&quot;><input type=&quot;reset&quot; value=&quot;Reset&quot; name=&quot;B2&quot;></p>
</form>

</body>
</html>
 
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This is a common problem with floating point math. Here's a &quot;quick and dirty&quot; way to handle that:

function calcTotal(form)
{
var total1, total2;

//multiply amount by 100 and round off
total1 = Math.round((StoreOrderForm.Qty1.value * StoreOrderForm.Price1.value) * 100);

//divide total by 100 and discard decimal, add decimal point, and add last 2 digits of total
StoreOrderForm.Total1.value = Math.floor(total1 / 100) + '.' + (total1 % 100);

total2 = Math.round((StoreOrderForm.Qty2.value * StoreOrderForm.Price2.value) * 100);

StoreOrderForm.Total2.value = Math.floor(total2 / 100) + '.' + (total2 % 100);

StoreOrderForm.Subtotal.value = Math.floor((total1 + total2) / 100) + '.' + ((total1 + total2( % 100);
}
 
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Thanks so much trollacious! You're awesome.
This has been driving me crazy. I really appreciate your help.

Jon
 
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