<pre class="shiki github-dark shaku"><code>// please complete the implementationclass EventEmitter { constructor() { this.subs = {} } subscribe(eventName, callback) { 	let index = 0 if(!this.subs[eventName]) { this.subs[eventName] = [callback] } else { this.subs[eventName].push(callback) index = this.subs[eventName].length - 1 } return { release: () =&gt; { this.subs[eventName] = this.subs[eventName].map((_, i) =&gt; { if(i === index) return null return _ }) if(this.subs[eventName].length &lt; 1) this.subs[eventName] = undefined } } } emit(eventName, ...args) { 	if(this.subs[eventName].length) { this.subs[eventName].forEach(e =&gt; { if(e) { e(...args) } }) } }}const callback1 = () =&gt; { console.log(1)}const callback2 = () =&gt; { console.log(2)}const emitter = new EventEmitter()const sub1 = emitter.subscribe('event1', callback1)const sub2 = emitter.subscribe('event2', callback2)// same callback could subscribe // on same event multiple timesconst sub3 = emitter.subscribe('event1', callback1)sub1.release()emitter.emit('event1', 1, 2);sub3.release()emitter.emit('event1', 1, 2);</code></pre>

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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…