Printing Event Object from an Arrow Function

Question

If I want to print the event object in Node.js using a callback function, this works:

Example 1

const events = require( 'events' );

var eventEmitter = new events.EventEmitter();

eventEmitter.on( 'customEventNameGoesHere', function() {
    console.log( this );
} );

eventEmitter.emit( 'customEventNameGoesHere' );

/* Sample output:
EventEmitter {
  _events:
   [Object: null prototype] { customEventNameGoesHere: [Function] },
  _eventsCount: 1,
  _maxListeners: undefined }
*/

However, if I try using an arrow function, it doesn't work:

Example 2

const events = require( 'events' );

var eventEmitter = new events.EventEmitter();

eventEmitter.on( 'customEventNameGoesHere', () => { console.log( this ); } );

eventEmitter.emit( 'customEventNameGoesHere' );

/* Sample output:
{}
*/

What do I need to change in Example 2 to print the value of the event object using the keyword "this"? Trying to access the local value of "this" instead of the parent value. How?

This happens due to lexical scoping. Arrow functions do not bind their own this,they inherit the one from the parent scope. — tiborK, May 22 '19 at 20:13
Possible duplicate of [Methods in ES6 objects: using arrow functions](https://stackoverflow.com/questions/31095710/methods-in-es6-objects-using-arrow-functions) — viz, May 22 '19 at 20:13
Is there a way to print the intended value of "this" using an arrow function in this context? — GTS Joe, May 22 '19 at 20:21
Its noted in the docs: https://nodejs.org/api/events.html#events_passing_arguments_and_this_to_listeners — Lawrence Cherone, May 22 '19 at 20:46
@LawrenceCherone I read the doc. It talks about the issue, but doesn't explain how to solve it. — GTS Joe, May 22 '19 at 20:50
Why do you need the arrow function? If your not needing parent scope? — Lawrence Cherone, May 22 '19 at 20:53

Printing Event Object from an Arrow Function

Example 1

Example 2

0 Answers0