eventhandler.js

/*
  eventhandler.js

  Simple event handler. Supports attaching events to callbacks and triggering
  events.

  TODO:
  Add a method for removing events.
*/


define(function() {

    var EventHandler = function(handlers) {
        this.handlers = {};
        for (event in handlers)
            this.on(event, handlers[event]);
    };

    EventHandler.prototype.on = function(events, handler, context) {
        if (typeof events === 'string')
            events = events.split(' ');
        if (context) {
            var _handler = handler;  // To avoid infinite recursion.
            handler = function() {_handler.apply(context, arguments)};
        }
        for (var i=0; i < events.length; i++) {
            var event = events[i];
            if (event in this.handlers)
                this.handlers[event].push(handler);
            else
                this.handlers[event] = [handler];
        }
    };

    EventHandler.prototype.emit = function(event, args) {
        var handlers = this.handlers[event];
        if (handlers)
            for (var i=0; i < handlers.length; i++)
                handlers[i].apply(null, Array.prototype.slice.call(arguments, 1));
    };

    return EventHandler;
});