<form action="" onsubmit="return false">
  <table>
    <thead><tr><td>Наименование</td><td>Цена</td></tr></thead>
    <tbody>
      <tr>
        <td><input type="text"></td>
        <td><input type="text"></td>
      </tr>
    </tbody>
  </table>

  <button type="button">Добавить</button>    
</form>

window.addEventListener('click', selected, false);
function selected(e) {
  e.preventDefault(); 
  e.stopImmediatePropagation();
  
  if ( e.target.tagName == 'BUTTON' ) console.log(e.target);
}