Event Delegation for Prototype

colin — Mon, 23 Mar 2009 23:16:48 +0000

Today I’d like to present my own rendition of an Event Delegator class based on Prototype. Event Delegation can be used to improve performance and code simplicity by observing one parent element and triggering events on the children when applicable rather than observing each child element individually.

This has the added benefit that new child elements do not require new event observers, and removed child elements do not create memory leaks or require any cleanup. My event delegator class supports both CSS selectors for this purpose as well as binary functions. An example usage scenario is with my ToolTip class. Fancy Javascript tooltips can be added and removed from a page for free, even as the result of an Ajax update by simply adding a recognized CSS class.

This was actually written back in July ’08, but I’d like to post it here now. It could use a little more thorough documentation, but here it is:

Ajax.DoubleCombo update

colin — Tue, 11 Nov 2008 09:30:15 +0000

Due to a recent request about my Ajax.DoubleCombo class, I have updated it to support automatic updates trickling down when the server returns a “selected” value or the default value is non-void. In the process, I added some Prototype 1.6 custom events, namely doubleCombo:update and doubleCombo:clearSlaves which in turn added support for what I will call “branching”. That is, support for multiple slave selects at each level. I don’t know if anyone has a use for this but it is now supported…

Here is the page with the code, docs and demo: Ajax.DoubleCombo

Colin Mollenhour's Technical Blog » prototype

Event Delegation for Prototype

Ajax.DoubleCombo update