title: Using a document level event listener instead of separated ones
body: <p>Imagine the following use case:</p>
  
  <p>A page contains a multitude of buttons, each of them triggers different functions. The examples what I saw added event listeners to every button.</p>
  
  <p>However what will happen if I add an event listener to the whole document, then extract the given element from the point, so I know what was clicked, and call a function accordingly.</p>
  
  <p>In that case there is only one event listener, and not as many as number of the buttons.</p>
  
  <p>Will this method give me performance gain?</p>