How the create an event handler similar to Bangle.on("step"...........)

Hi,

I would like to create my own event handlers similar like the Bangle event handlers, f.i. the "step" handler.

Bangle.on('step', function(up) {
  print("step was made");
});

Tried this example from https://www.w3schools.com/nodejs/nodejs_events.asp

var events = require('events');
var eventEmitter = new events.EventEmitter();

//Create an event handler:
var myEventHandler = function () {
  console.log('I hear a scream!');
};

//Assign the event handler to an event:
eventEmitter.on('scream', myEventHandler);

//Fire the 'scream' event:
eventEmitter.emit('scream');

But this results in the error:

I read in the Espruino documentation here http://www.espruino.com/Reference#l_Object_emit about Object.emit and Object.on but can not find any reference or example on how to setup an eventEmitter in Espruino.

I'm rather new to Espruino/Javascript so maybe there's an obvious answer. Can someone point me in the right direction?