@throneless/libsignal-service/src/EventTarget.js

A fork of the the libtextsecure components of Signal-Desktop, adapted for use by nodejs.

/*
 * vim: ts=2:sw=2:expandtab
 */



// eslint-disable-next-line func-names

const Event = require('./Event.js');

class 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;
  }
}

exports = module.exports = EventTarget;