Writing custom emitter's in nodejs

app.js

// let's code some emitters 
function Emitter(){
    this.events = {};
}

const emtr = new Emitter();

// on function to push events in array 
Emitter.prototype.on = function(type,listener){
    this.events[type] = this.events[type] || [];
    this.events[type].push(listener);
}

// when you want to emit 
Emitter.prototype.emit = function(type){
    if(this.events[type]){
        this.events[type].forEach(listener => {
            listener();
        });
    }
}

// adding events to array 
emtr.on("Namastey",()=>{
    console.log("That's Hi in Hindi");
})

// emitting the events 
emtr.emit("Namastey"); // this will print console 
emtr.emit("Sss"); // and this won't