<pre class="shiki github-dark shaku"><code>// please complete the implementationclass EventEmitter { store = new Map(); // [eventName, new Map([uuid, callback])] uuid = 0; subscribe(eventName, callback) { const store = this.store const uuid = this.uuid if (!store.has(eventName)) { store.set(eventName, new Map()) } const eventCallbacks = store.get(eventName) eventCallbacks.set(uuid, callback) this.uuid++ return { // IIFE. uuid is copied in the scope // this way we can distinguish the subscribers // even if they look identical release: () =&gt; (function (uuid) { if (!store.has(eventName)) return if (!store.get(eventName).has(uuid)) return store.get(eventName).delete(uuid) if (store.get(eventName).size == 0) { store.delete(eventName) } })(uuid) } } emit(eventName, ...args) { const eventCallbacks = this.store.get(eventName) if (!eventCallbacks) return for (let [_, callback] of eventCallbacks.entries()) { callback(...args) } }}// Test casesconst emitter = new EventEmitter()const callback1 = (...args) =&gt; console.log('called', ...args)const sub1 = emitter.subscribe('event', callback1)const sub2 = emitter.subscribe('event', callback1)sub1.release()sub1.release()sub1.release()emitter.emit('event', 'sub2 should receive it')</code></pre>

The correct answer. It should distinguish the same callback by uuid

TikTok

Microsoft

Flipkart

There is Event Emitter in Node.js, Facebook once had its own implementation but now it is archived. You are asked to create an Event Emitter Class con…