Listener for clicks outside the element, for example, for closing menus on outside click.

outside_click.js

var el = document.getElementById('el');

document.addEventListener('click', outsideEvtListener);

function outsideEvtListener(evt) {
    if (evt.target === el || el.contains(evt.target)) {
        return;
    }
    // code handling outside click
   
    // removing the listener to avoid memory leaks
    document.removeEventListener('click', outsideEvtListener);
}