Another approach, which is the standard way since DOM2 to bind this within the event listener, that let you always remove the listener (among other benefits), is the handleEvent(evt)method from the EventListener interface:

var obj = {
  handleEvent(e) {
    // always true
    console.log(this === obj);
  }
};

document.body.addEventListener('click', obj);

Detailed information about using handleEvent can be found here: https://medium.com/@WebReflection/dom-handleevent-a-cross-platform-standard-since-year-2000-5bf17287fd38

Another approach, which is the standard way since DOM2 to bind this within the event listener, that let you always remove the listener (among other benefits), is the handleEvent(evt) method from the EventListener interface:

var obj = {
  handleEvent(e) {
    // always true
    console.log(this === obj);
  }
};

document.body.addEventListener('click', obj);

Detailed information about using handleEvent can be found here: DOM handleEvent: a cross-platform standard since year 2000