EventListener.js

/**
 * Copyright 2013-2015, Facebook, Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 * @providesModule EventListener
 * @typechecks
 */

var emptyFunction = require("./emptyFunction");

/**
 * Upstream version of event listener. Does not take into account specific
 * nature of platform.
 */
var EventListener = {
  /**
   * Listen to DOM events during the bubble phase.
   *
   * @param {DOMEventTarget} target DOM element to register listener on.
   * @param {string} eventType Event type, e.g. 'click' or 'mouseover'.
   * @param {function} callback Callback function.
   * @return {object} Object with a `remove` method.
   */
  listen: function(target, eventType, callback) {
    if (target.addEventListener) {
      target.addEventListener(eventType, callback, false);
      return {
        remove: function() {
          target.removeEventListener(eventType, callback, false);
        }
      };
    } else if (target.attachEvent) {
      target.attachEvent('on' + eventType, callback);
      return {
        remove: function() {
          target.detachEvent('on' + eventType, callback);
        }
      };
    }
  },

  /**
   * Listen to DOM events during the capture phase.
   *
   * @param {DOMEventTarget} target DOM element to register listener on.
   * @param {string} eventType Event type, e.g. 'click' or 'mouseover'.
   * @param {function} callback Callback function.
   * @return {object} Object with a `remove` method.
   */
  capture: function(target, eventType, callback) {
    if (!target.addEventListener) {
      if ("production" !== process.env.NODE_ENV) {
        console.error(
          'Attempted to listen to events during the capture phase on a ' +
          'browser that does not support the capture phase. Your application ' +
          'will not receive some events.'
        );
      }
      return {
        remove: emptyFunction
      };
    } else {
      target.addEventListener(eventType, callback, true);
      return {
        remove: function() {
          target.removeEventListener(eventType, callback, true);
        }
      };
    }
  },

  registerDefault: function() {}
};

module.exports = EventListener;