I am a big fan of both Andrew Dupont, and custom events.
In his presentation he goes through some very nice use cases. Some are cross cutting (e.g. the fact that you can unit test, or debug, or … so much easier) and some are specific such as:
Scripty2 animation heartbeat
setTimeout(function() {
document.fire(“effect:heartbeat”);
}, 0);
// listen in
document.observe(“effect:heartbeat”, advanceEffectByOneFrame);
// allows for nice debugging
document.observe(“keydown”, function(event) {
if (event.keyCode === Event.KEY_RIGHT) {
document.fire(“effect:heartbeat”);
}
});
Another nice example is how you can start using the new and cool EventSource while retrofitting the functionality for browsers who don’t implement the new standard:
var eventSource = $(‘event_source’);
eventSource.observe(‘server-sent-event-name’, function(event) {
document.fire(‘data:received’, event.data);
});
// old browsers
new Ajax.Request(‘/legacy/polling’, {
onComplete: function(request) {
document.fire(‘data:received’, request.responseJSON);
}
});
// observer works for both
$(document).observe(‘data:received’, function(event) {
doStuff(event.memo);
});
And, there are many more great examples in the slides.
How have you been using custom events?
