40 lines
846 B
JavaScript
40 lines
846 B
JavaScript
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class EventEmitter {
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constructor() {
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this.mapping = new Map();
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}
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subscribe(event, cb) {
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if (!this.mapping.has(event)) {
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this.mapping.set(event, new Array());
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}
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this.mapping.get(event).push(cb);
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return {
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unsubscribe: () => {
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this.mapping.set(event, this.mapping.get(event).filter(s => s !== cb));
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}
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};
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}
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emit(event, args = []) {
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if (!this.mapping.has(event)) {
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return [];
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}
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return this.mapping.get(event).map(cb => cb(...args));
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}
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}
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/**
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* const emitter = new EventEmitter();
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*
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* // Subscribe to the onClick event with onClickCallback
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* function onClickCallback() { return 99 }
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* const sub = emitter.subscribe('onClick', onClickCallback);
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*
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* emitter.emit('onClick'); // [99]
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* sub.unsubscribe(); // undefined
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* emitter.emit('onClick'); // []
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*/
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