react-native/Libraries/Device/NativeEventEmitter.js

67 lines
1.9 KiB
JavaScript

/**
* Copyright (c) 2015-present, Facebook, Inc.
* All rights reserved.
*
* This source code is licensed under the BSD-style license found in the
* LICENSE file in the root directory of this source tree. An additional grant
* of patent rights can be found in the PATENTS file in the same directory.
*
* @providesModule NativeEventEmitter
* @flow
*/
'use strict';
const Platform = require('Platform');
const RCTDeviceEventEmitter = require('RCTDeviceEventEmitter');
const invariant = require('fbjs/lib/invariant');
import type EmitterSubscription from 'EmitterSubscription';
/**
* Abstract base class for implementing event-emitting modules. This implements
* a subset of the standard EventEmitter node module API.
*/
class NativeEventEmitter {
_nativeModule: Object;
constructor(nativeModule: Object) {
if (Platform.OS === 'ios') {
invariant(nativeModule, 'Native module cannot be null.');
this._nativeModule = nativeModule;
}
}
addListener(eventType: string, listener: any, context: ?Object): EmitterSubscription {
if (Platform.OS === 'ios') {
this._nativeModule.addListener(eventType);
}
return RCTDeviceEventEmitter.nativeAddListener(eventType, listener, context);
}
once(eventType: string, listener: any, context: ?Object): EmitterSubscription {
return this.addListener(eventType, () => {
this.removeCurrentListener();
listener.apply(context, arguments);
});
}
removeAllListeners(eventType: string) {
invariant(eventType, 'eventType argument is required.');
if (Platform.OS === 'ios') {
const count = RCTDeviceEventEmitter.listeners(eventType).length;
this._nativeModule.removeListeners(count);
}
RCTDeviceEventEmitter.removeAllListeners(eventType);
}
removeCurrentListener() {
if (Platform.OS === 'ios') {
this._nativeModule.removeListeners(1);
}
RCTDeviceEventEmitter.removeCurrentListener();
}
}
module.exports = NativeEventEmitter;