index.html

<form>FORM
  <div>DIV
    <p>P</p>
  </div>
</form>

index.js

function handleEvent(event) {
  alert(event.currentTarget);
}

var form = document.querySelector('form');
var div = document.querySelector('div');
var p = document.querySelector('p');

form.addEventListener('click', handleEvent);
div.addEventListener('click', handleEvent);
p.addEventListener('click', handleEvent);