[development] Drupal way of doing onchange

[Jeff Greenberg]

Haven't delved into AHAH yet, this might force the issue.


Using an easy (=less typing) example. A credit card form. When the 
credit card type is selected from a select, the selection needs to fire 
a javascript function that will disable fields that don't apply to that 
card type (such as CVV).


Normally, I would have an onchange event for the select, and noticed 
that in the form api, while there is an attribute section to add 
miscellaneous attributes, the doc doesn't mention events as examples. 
And if putting an event there is legitimate, there isn't a mention of 
how to include the responding js function in the form.


If AHAH is the way I'm supposed to handle this, I'd appreciate being 
pointed to a good similar example, because I'm a bit unclear from the 
AHAH entries in the form reference docs, for example, how to relate the 
myhandler/js entry to a physical location of the function, and how the 
function gets there.


Thanks!