I'm using Flash a lot and my classes uses EventDispatcher class which allows me to define custom events of a class. How can I do this in JavaScript.
I would like to do something like this:
var MyClass = function() {
};
MyClass.prototype = {
test : function() {
dispatchEvent('ON_TEST');
}
};
var mc = new MyClass();
mc.addEventListener('ON_TEST', handler);
function handler() { alert('working...') }
How is this possible with JavaScript?
Gotta roll your own. Here's just one way.
var MyClass = function() {
this._events = {};
};
MyClass.prototype = {
addListener: function(eventName, callback) {
var events = this._events,
callbacks = events[eventName] = events[eventName] || [];
callbacks.push(callback);
},
raiseEvent: function(eventName, args) {
var callbacks = this._events[eventName];
for (var i = 0, l = callbacks.length; i < l; i++) {
callbacks[i].apply(null, args);
}
},
test : function() {
this.raiseEvent('ON_TEST', [1,2,3]); // whatever args to pass to listeners
}
};
You should probably also add a 'removeListener', which would have to find the callback in the array and remove it from the array (or possibly, remove all listeners for an entire event if no callback given).
function (eventName, callback) { (this._events[eventName] = this._events[eventName] || []).push(callback); }, ? or is it merely a question of readability?