@lightningtv/renderer
Version:
Lightning 3 Renderer
66 lines • 1.99 kB
JavaScript
/*
* If not stated otherwise in this file or this component's LICENSE file the
* following copyright and licenses apply:
*
* Copyright 2023 Comcast Cable Communications Management, LLC.
*
* 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.
*/
/**
* EventEmitter base class
*/
export class EventEmitter {
eventListeners = {};
on(event, listener) {
let listeners = this.eventListeners[event];
if (!listeners) {
listeners = [];
}
listeners.push(listener);
this.eventListeners[event] = listeners;
}
off(event, listener) {
const listeners = this.eventListeners[event];
if (!listeners) {
return;
}
if (!listener) {
delete this.eventListeners[event];
return;
}
const index = listeners.indexOf(listener);
if (index >= 0) {
listeners.splice(index, 1);
}
}
once(event, listener) {
const onceListener = (target, data) => {
this.off(event, onceListener);
listener(target, data);
};
this.on(event, onceListener);
}
emit(event, data) {
const listeners = this.eventListeners[event];
if (!listeners) {
return;
}
[...listeners].forEach((listener) => {
listener(this, data);
});
}
removeAllListeners() {
this.eventListeners = {};
}
}
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