session-desktop/libtextsecure/event_target.js

83 lines
2.4 KiB
JavaScript

/* global window, Event, textsecure */
/*
* Implements EventTarget
* https://developer.mozilla.org/en-US/docs/Web/API/EventTarget
*/
// eslint-disable-next-line func-names
(function() {
window.textsecure = window.textsecure || {};
function EventTarget() {}
EventTarget.prototype = {
constructor: EventTarget,
dispatchEvent(ev) {
if (!(ev instanceof Event)) {
throw new Error('Expects an event');
}
if (this.listeners === null || typeof this.listeners !== 'object') {
this.listeners = {};
}
const listeners = this.listeners[ev.type];
const results = [];
if (typeof listeners === 'object') {
for (let i = 0, max = listeners.length; i < max; i += 1) {
const listener = listeners[i];
if (typeof listener === 'function') {
results.push(listener.call(null, ev));
}
}
}
return results;
},
addEventListener(eventName, callback) {
if (typeof eventName !== 'string') {
throw new Error('First argument expects a string');
}
if (typeof callback !== 'function') {
throw new Error('Second argument expects a function');
}
if (this.listeners === null || typeof this.listeners !== 'object') {
this.listeners = {};
}
let listeners = this.listeners[eventName];
if (typeof listeners !== 'object') {
listeners = [];
}
listeners.push(callback);
this.listeners[eventName] = listeners;
},
removeEventListener(eventName, callback) {
if (typeof eventName !== 'string') {
throw new Error('First argument expects a string');
}
if (typeof callback !== 'function') {
throw new Error('Second argument expects a function');
}
if (this.listeners === null || typeof this.listeners !== 'object') {
this.listeners = {};
}
const listeners = this.listeners[eventName];
if (typeof listeners === 'object') {
for (let i = 0; i < listeners.length; i += 1) {
if (listeners[i] === callback) {
listeners.splice(i, 1);
return;
}
}
}
this.listeners[eventName] = listeners;
},
extend(obj) {
// eslint-disable-next-line no-restricted-syntax, guard-for-in
for (const prop in obj) {
this[prop] = obj[prop];
}
return this;
},
};
textsecure.EventTarget = EventTarget;
})();