Commnets

1. Frank Manno Says: July 5th, 2009 at 10:07 am

   Tim,

   Thanks for clearing that up. I thought that’s what it was… I should have checked the YUI APIs before posting

   Care to share more about the nested CustomEvents? It sounds interesting…

2. David Fitch Says: July 5th, 2009 at 12:07 pm

   This is great, thanks for your contribution!

   I’m what I consider to be a novice with javascript, and OOP in general, so I was having a LOT of trouble figuring out how to fire two separate requests intended to populate two separate divs, using one event. I stumbled across this, and voila! I modified the connect method slightly to allow for passing of ‘targetDiv’, so I can trigger both of the following onLoad:

   myAjaxEvent.connect(’groups-test.asp?action=add’,’divDataDisplay’);
   myAjaxEvent.connect(’groups-edit-test.asp’,’divDataAddEdit’);

   And then replaced the JSON stuff with a simple getElementById(targetDiv).innerHTML = o.responseText

   Thanks again!!!

3. Tim Says: July 6th, 2009 at 1:07 am

   @ Frank: The “ajaxevent” that is passed as the first parameter into the YUI YAHOO.util.CustomEvent constructor is, as you suspect, simply an identifier for the CustomEvent. This string is returned to listeners that receive this event so that they know what event occurred.

   I’m not sure you’d need different event names per AjaxEvent object since they will all be of the type “ajaxevent” — it simply identifies the type of event. Of course, there’s no reason why they couldn’t be nested inside other CustomEvents though; for instance, we’ve recently been using them inside a “tabactivated” event inside a tab module.

4. Frank Manno Says: July 7th, 2009 at 3:07 am

   Tim,

   Nice script! I think the example greatly demonstrates the usefulness of this type of event system.

   One thing regarding the “subscribe” function. In the YAHOO.util.CustomEvent constructor, you pass “ajaxevent” as the first parameter. Does this mean anything in terms of the application, or is it simply an identifier?

   I’m just curious as to whether you would need custom “AjaxEvent” objects that use different event names?

5. Tim Says: July 7th, 2009 at 7:07 am

   @ Marco: When we first started developing this idea, we originally created AjaxEvent as a singleton. However, it soon became apparent that it needed to be instantiable to maintain several of the properties when handling multiple requests.

   I’m not sure that wrapping these instantiated objects inside another singleton would be such a good idea — there are many benefits to be had by allowing those instantiations to be inherited by other objects elsewhere.

   As far as recycling eval’d JSON responses is concerned, there’s really no reason why we couldn’t check it against the response within the AjaxEvent object itself. It’s a nice idea and one I shall look into.

6. Marco Says: July 8th, 2009 at 1:07 am

   Very nice article and code example!

   I was wondering whether this whole idea can’t be taken to an even higher level by creating some sort of singleton which holds all of these AJAX events + connections. Like this it might even be possible to recycle eval-ed JSON responses in cases where it’s unlikely that the server response changes between requests to the exact same URL (for example gimmesomejson.php?skeleton=24) if we’d store the response. This could possibly speed up the application and reduce server load.

   Not sure if this makes sense, it’s saturday morning after all, but maybe it’s worth looking into?

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