[Dilettante_Pro]

<span value = "user">1</span>
<span value = "user">2</span>
<span value = "user">20</span>  
<button onclick="changeText();">Change</button>
<script src="https://code.jquery.com/jquery-latest.min.js"></script>
<script>
function changeText() {
  $("span[value='user']").each(function() {
     $(this).text(+$(this).text() + 1);
  });
}
</script>