Need help with code

I may be able to offer a little help whilst you wait for the experts!
This is a code I use...

<script>

var vv = document.editform.value_unit_price;

var ww = document.editform.value_quantity;

vv.onchange = vv.onkeyup =ww.onchange = ww.onkeyup =function() {

var qty = document.editform.value_quantity.value;

var unit = document.editform.value_unit_price.value;

document.editform.value_net_value.value =parseFloat(qty)*parseFloat(unit);}

</script>

With your code...

x.onchange = x.onkeyup = function(){

var Invoice_Amount = document.forms.editform.value_Invoice_Amount.value;

document.forms.editform.value_Purchase_Amount.value = Number(Invoice_Amount) ;}

</script>{/literal}

Have you started with {literal}<script>?You may be able to remove literals depending on which phprunner you are using.

Also have you defined the var invoice - see first line of my code.
Hope this helps

I may be able to offer a little help whilst you wait for the experts!

This is a code I use...
With your code...
Have you started with {literal}<script>?You may be able to remove literals depending on which phprunner you are using.

Also have you defined the var invoice - see first line of my code.
Hope this helps

Hello Thanks ,
Looks like some of my code got chopped off tried your code but I must be doing something wrong must admit I'm bit of a newbie can you post a example how you would combine the code I just can't get my head around it any help would be great below is the full block of code that is working and that I want to expand on thanks in advance.
[codebox]{literal}<script>

var x = document.forms.editform.value_Invoice_Amount;

x.onchange = x.onkeyup = function()

{

var Invoice_Amount = document.forms.editform.value_Invoice_Amount.value;
document.forms.editform.value_Purchase_Amount.value = Number(Invoice_Amount) ;

}

</script>{/literal}[/codebox]
Regards,

racerx