day 28 task complete

Author: Sanchitbajaj02

day28/leetcode2629.js

@@ -0,0 +1,58 @@
+// 2694. Event Emitter
+// URL -> https://leetcode.com/problems/event-emitter
+
+class EventEmitter {
+  constructor() {
+    this.eventRecords = {}
+  }
+  /**
+   * @param {string} eventName
+   * @param {Function} callback
+   * @return {Object}
+   */
+  subscribe(eventName, callback) {
+    if (!this.eventRecords.hasOwnProperty(eventName)) {
+      this.eventRecords[eventName] = []
+    }
+
+    let cbList = this.eventRecords[eventName]
+    cbList.push(callback);
+
+    return {
+      unsubscribe: () => {
+        const index = cbList.indexOf(callback)
+        cbList.splice(index, 1)
+      }
+    };
+  }
+
+  /**
+   * @param {string} eventName
+   * @param {Array} args
+   * @return {Array}
+   */
+  emit(eventName, args = []) {
+    if (!this.eventRecords.hasOwnProperty(eventName)) {
+      return []
+    }
+    let result = []
+    let cbList = this.eventRecords[eventName]
+
+    for (let cb of cbList) {
+      result.push(cb(...args))
+    }
+    return result
+  }
+}
+
+/**
+* const emitter = new EventEmitter();
+*
+* // Subscribe to the onClick event with onClickCallback
+* function onClickCallback() { return 99 }
+* const sub = emitter.subscribe('onClick', onClickCallback);
+*
+* emitter.emit('onClick'); // [99]
+* sub.unsubscribe(); // undefined
+* emitter.emit('onClick'); // []
+*/