How to programmatically fire a dblclick event defined with addEventListener?

You can use dispatchEvent to programatically trigger events:

var event = new MouseEvent('dblclick', {
    'view': window,
    'bubbles': true,
    'cancelable': true
  });
document.getElementById('aa').dispatchEvent(event);

See the section "Triggering built-in events" on MDN.

Here is a fiddle of the code in action.

This should work:

var doubleClickEvent = document.createEvent('MouseEvents');
doubleClickEvent.initEvent('dblclick', true, true);
e.currentTarget.dispatchEvent(doubleClickEvent); // inside method