Edit in JSFiddle

var on = function(node, evtName, nodeName, callback){
	node.addEventListener(evtName, function(e){
  	var target = e.target;
    while(target !== null){
      if(target.nodeName === nodeName.toUpperCase()){
				callback.call(target, e);
        break;
      }
      target = target.parentNode;
    }
  });
};

on(document, 'click', 'strong', function(e){
	this.style.border = '1px solid red';
})
<div>
  <p>
    <strong>
      <small>test</small>
    </strong>
  </p>
  
  <p>
    <strong>
      <small>test</small>
    </strong>
  </p>

  <p>
    <strong>
      <small>test</small>
    </strong>
  </p>
</div>