Javascript Custom event emitter

tags: JavaScript

Create Custom Event Emitter with javascript

class EventEmitter {
  constructor() {
    this._events = {};
  }

  on(name, listener) {
    if (!this._events[name]) {
      this._events[name] = [];
    }

    this._events[name].push(listener);
  }

  delete(name) {
    if (this._events[name]) {
      delete this._events[name];
    }
  }

  removeListener(name, listenerToRemove) {
    if (!this._events[name]) {
      throw new Error(
        `Can't remove a listener. Event "${name}" doesn't exits.`
      );
    }

    const filterListeners = listener => listener !== listenerToRemove;

    this._events[name] = this._events[name].filter(filterListeners);
  }

  emit(name, ...data) {
    if (!this._events[name]) {
      throw new Error(`Can't emit an event. Event "${name}" doesn't exits.`);
    }

    this._events[name].forEach(callback => callback(data));
  }
}

let ev = new EventEmitter();
ev.on("hello", val => {
  console.log("event from emiiter ", val);
});

const handleMyEvent = data => {
  console.log("Was fired: ", data);
};

ev.emit("hello", { name: "shri" }, handleMyEvent);
// ev.delete("hello");

ev.emit("hello", { name: "shri" }, handleMyEvent);

Demo link