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60 lines
1.7 KiB
60 lines
1.7 KiB
/* |
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Copyright 2019 Google LLC |
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Use of this source code is governed by an MIT-style |
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license that can be found in the LICENSE file or at |
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https://opensource.org/licenses/MIT. |
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*/ |
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/** |
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* A minimal `EventTarget` shim. |
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* This is necessary because not all browsers support constructable |
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* `EventTarget`, so using a real `EventTarget` will error. |
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* @private |
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*/ |
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export class WorkboxEventTarget { |
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constructor() { |
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this._eventListenerRegistry = new Map(); |
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} |
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/** |
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* @param {string} type |
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* @param {Function} listener |
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* @private |
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*/ |
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addEventListener(type, listener) { |
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const foo = this._getEventListenersByType(type); |
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foo.add(listener); |
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} |
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/** |
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* @param {string} type |
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* @param {Function} listener |
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* @private |
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*/ |
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removeEventListener(type, listener) { |
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this._getEventListenersByType(type).delete(listener); |
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} |
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/** |
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* @param {Object} event |
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* @private |
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*/ |
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dispatchEvent(event) { |
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event.target = this; |
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const listeners = this._getEventListenersByType(event.type); |
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for (const listener of listeners) { |
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listener(event); |
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} |
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} |
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/** |
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* Returns a Set of listeners associated with the passed event type. |
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* If no handlers have been registered, an empty Set is returned. |
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* |
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* @param {string} type The event type. |
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* @return {Set<ListenerCallback>} An array of handler functions. |
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* @private |
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*/ |
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_getEventListenersByType(type) { |
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if (!this._eventListenerRegistry.has(type)) { |
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this._eventListenerRegistry.set(type, new Set()); |
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} |
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return this._eventListenerRegistry.get(type); |
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} |
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}
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