Recommended way to keep multiple event handlers?

[Sol Mayer-Orn]

Hi,

Could anyone please recommend a design approach for keeping more than 1 event handler, for the same event ?
In particular, could you keep such handlers un-aware of each other?

Simplified example:
Say I started off with 2 independent requirements for a text input's "onkeyup()" :
- Some text-inputs should only allow lower-case letters
- Other(!) text-inputs should sound a 'beep' while tying.
Then this works:

     // Constructor for 'lowercase' hanlder : registers 'onkyup' handler:
     function LowerCaseHandler( textInput){
         textInput.onkeyupp=function(){ ... /* convert to lowercase*/ }
     }
 
     // Constructor for 'beep' hanlder : registers 'onkyup' handler:
     function BeepHandler( textInput, beepDuration){
         this.beepDuration = beepDuration;
         textInput.onkeyupp=function(){ ... /* beep for 'beepDuration' seconds */ }
     }
 

However, later the requirements evolve, and *some* text-inputs need both effects (beep & lowercase). While other fields need a single effect (eg. just beep).
Of course, I could write a new 'onkeyup()' function that performs both actions (beep and lowercase).
But I really wish I could make it cleaner:

// This doesn't work (the last 'onkeyup' handler overrides the first one).
// But I strive to get as close as possible to this: no additional functions, 
// and handlers are not aware of each other.
var myTextInput = document.myForm.myTextInput;
new LowerCaseHandler(myTextInput );
new BeepHandler(myTextInput );

In real life my 'Handlers' are more complex, there are more Handlers and more combinations.
What is the best way to allow such combinations, while keeping my handlers un-aware of each other?

Thanks very much!

[ March 15, 2007: Message edited by: Sol Mam-Orn ]
[ March 15, 2007: Message edited by: Sol Mam-Orn ]

[Bear Bibeault]

Using DOM Level 0 Event handling, you are pretty much out of luck. At least not without a lot of mess.

Using the DOM Level 2 Event Model allows you to register multiple and independent handlers. The drawback is that it's browser dependent: there's the standard W3C way, and the Microsoft "we don't need no stinking standards" way.

Use of a library such as Prototype or jQuery eases the pain considerably.

[Sol Mayer-Orn]

Thanks very much

[Eric Pascarello]

Take a look at this: http://www.pascarello.com/examples/testRegister.html

Eric