onClickOutside

Runs the callback whenever the user clicks outside of the specified element.

• Use EventTarget.addEventListener() to listen for 'click' events.
• Use Node.contains() to check if Event.target is a descendant of element and run callback if not.

const onClickOutside = (element, callback) => {
  document.addEventListener('click', e => {
    if (!element.contains(e.target)) callback();
  });
};

onClickOutside('#my-element', () => console.log('Hello'));
// Will log 'Hello' whenever the user clicks outside of #my-element