simple javascript nightmare

techtimmy · 22-06-2010, 03:16:28 PM

Hopefully really easy for someone with even a basic understanding of javascript.

I've 'written'

a function which collects the info from a form field:

Quote:

var justhow;
function calculate(select)
{
justhow = document.forms[0].howmany.value;
}

When i try to call the bugger later on

Quote:

document.write('<input type="text" name="total" size="10" value="' + justhow + '">');

it comes back as undefined.

I know it works fine as if I move the document.write into the function it does the calculation (but in a new page?!?!?)

I thinkits something to do with global/local variables but after reading about 50 different tutorials its still not working.

Can anyone help?

Thanks

StudioVision · 23-06-2010, 01:38:32 AM

Hi

This should help:

Quote:

var justhow;
function calculate(){
justhow = document.getElementById('howmany').value;
document.getElementById('total').value = justhow;
}

Then in your page you would need the following form fields:

Quote:

Whenever the value of field id "howmany" is changed, the value of field id "total" will be updated.

Hope this helps!

Craig

techtimmy · 23-06-2010, 09:35:49 AM

Awesome skillz dude.

Many many thanks

StudioVision · 23-06-2010, 04:37:54 PM

No worries, glad it helped!

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23-06-2010, 09:35:49 AM	#3 (permalink)
techtimmy Join Date: Mar 2008 Posts: 328 No Classified Ratings Domain Trader Rating: (100% / 4)	Awesome skillz dude. Many many thanks

23-06-2010, 04:37:54 PM	#4 (permalink)
StudioVision Join Date: Jan 2007 Location: Barnsley, South Yorkshire Posts: 523 No Classified Ratings Domain Trader Rating: (100% / 22)	No worries, glad it helped!