onchange without losing focus?

Question

I'm creating a form with a select dropdown. One of the options is "other - please specify", which is supposed to display an extra text field for more details.

I managed to do it using onChange event + some simple value check (as I can't rely on the position).

I started testing it and realized that while it works perfectly when using a mouse (onChange is ran after the control loses focus), it doesn't when I use the keyboard (since it didn't lose focus yet) - only after I press tab do the changes appear (which looks weird).

It seems to me like I'm missing something obvious, I looked for other events and the closest I've found is onclick, but that's not it either.

So the question is, is there a better way of solving this?

Answer 1

This article might help you. It uses tricks like so:

// executes an onchange function after 750ms (or specified delay)
function safeOnChange1( code, delay ) {
  delay = delay || 750;
  window.clearTimeout( soc_id );
  soc_id = window.setTimeout( code, delay );
} 
// global timer ID for the safeOnChange1 function.
var soc_id = null;

It's not pretty but that's the problem with using the onchange function on a dropdown. The other solution would be a function checking the value of the dropdown every once in a while and calling the onchange function if it changed.

Look up tutorials like this: http://onlinetools.org/articles/unobtrusivejavascript/chapter4.html

function addEvent(obj, evType, fn){ 
 if (obj.addEventListener){ 
   obj.addEventListener(evType, fn, false); 
   return true; 
 } else if (obj.attachEvent){ 
   var r = obj.attachEvent("on"+evType, fn); 
   return r; 
 } else { 
   return false; 
 } 
}
addEvent(window, 'load', foo);
addEvent(window, 'load', bar);

There's also a jquery way if you can look it up