47 lines
1.2 KiB
JavaScript
47 lines
1.2 KiB
JavaScript
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/*
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* async Event Emitter
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*
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* // Example usage
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* const emitter = new AsyncEmitter();
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*
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* // Register some async listeners
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* emitter.on("data", async (msg) => {
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* console.log("Listener 1 starting...");
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* await new Promise((r) => setTimeout(r, 1000));
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* console.log("Listener 1 done:", msg);
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* });
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*
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* emitter.on("data", async (msg) => {
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* console.log("Listener 2 starting...");
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* await new Promise((r) => setTimeout(r, 500));
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* console.log("Listener 2 done:", msg);
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* });
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*
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* (async () => {
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* console.log("Emitting...");
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* await emitter.emit("data", "Hello async world!");
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* console.log("All listeners finished.");
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* })();
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*/
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class AsyncEmitter {
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constructor() {
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this.listeners = new Map();
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}
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on(event, listener) {
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if (!this.listeners.has(event)) this.listeners.set(event, []);
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this.listeners.get(event).push( listener );
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}
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async emit(event, ...args) {
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const listeners = this.listeners.get(event) || [];
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if( document.location.hostname == 'localhost' ) console.info(`emit(${event})`)
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for (const fn of listeners) {
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await fn(...args); // <-- Waits for each listener to finish
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}
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}
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}
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export {AsyncEmitter}
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