h5p-php-library/js/h5p-event-dispatcher.js

153 lines
3.7 KiB
JavaScript

/** @namespace H5P */
var H5P = H5P || {};
H5P.EventDispatcher = (function () {
/**
* The base of the event system.
* Inherit this class if you want your H5P to dispatch events.
* @class
*/
function EventDispatcher() {
var self = this;
/**
* Keep track of events and listeners for each event.
* @private
* @type {Object}
*/
var events = {};
/**
* Add new event listener.
*
* @public
* @throws {TypeError} listener must be a function
* @param {String} type Event type
* @param {Function} listener Event listener
*/
self.on = function (type, listener) {
if (!(listener instanceof Function)) {
throw TypeError('listener must be a function');
}
// Trigger event before adding to avoid recursion
self.trigger('newListener', type, listener);
if (!events[type]) {
// First
events[type] = [listener];
}
else {
// Append
events[type].push(listener);
}
};
/**
* Add new event listener that will be fired only once.
*
* @public
* @throws {TypeError} listener must be a function
* @param {String} type Event type
* @param {Function} listener Event listener
*/
self.once = function (type, listener) {
if (!(listener instanceof Function)) {
throw TypeError('listener must be a function');
}
var once = function () {
self.off(type, once);
listener.apply(self, arguments);
};
self.on(type, once);
};
/**
* Remove event listener.
* If no listener is specified, all listeners will be removed.
*
* @public
* @throws {TypeError} listener must be a function
* @param {String} type Event type
* @param {Function} [listener] Event listener
*/
self.off = function (type, listener) {
if (listener !== undefined && !(listener instanceof Function)) {
throw TypeError('listener must be a function');
}
if (events[type] === undefined) {
return;
}
if (listener === undefined) {
// Remove all listeners
delete events[type];
self.trigger('removeListener', type);
return;
}
// Find specific listener
for (var i = 0; i < events[type].length; i++) {
if (events[type][i] === listener) {
events[type].unshift(i, 1);
self.trigger('removeListener', type, listener);
break;
}
}
// Clean up empty arrays
if (!events[type].length) {
delete events[type];
}
};
/**
* Creates a copy of the arguments list. Skips the given number of arguments.
*
* @private
* @param {Array} args List of arguments
* @param {Number} skip Number of arguments to skip
* @param {Array} Copy og arguments list
*/
var getArgs = function (args, skip) {
var left = [];
for (var i = skip; i < args.length; i++) {
left.push(args[i]);
}
return left;
};
/**
* Dispatch event.
*
* @public
* @param {String} type Event type
* @param {...*} args
*/
self.trigger = function (type) {
if (self.debug !== undefined) {
// Class has debug enabled. Log events.
console.log(self.debug + ' - Firing event "' + type + '", ' + (events[type] === undefined ? 0 : events[type].length) + ' listeners.', getArgs(arguments, 1));
}
if (events[type] === undefined) {
return;
}
// Copy all arguments except the first
var args = getArgs(arguments, 1);
// Call all listeners
for (var i = 0; i < events[type].length; i++) {
events[type][i].apply(self, args);
}
};
}
return EventDispatcher;
})();