disposable event listener

addDisposableEventListener.js

if (!EventTarget.prototype.addDisposableEventListener) {
  EventTarget.prototype.addDisposableEventListener = function(type, listener, options) {
    this.addEventListener(type, listener, options);
    return () => this.removeEventListener(type, listener);
  }
}

const dispose = document.body.addDisposableEventListener(
  'click', () => console.log('clicked!'));
try {
  await new Promise(r => setTimeout(r, 5000));
} 
finally {
  dispose();
}