jQuery Selector How to - Select by id vs select by class name

Question

We would like to know how to select by id vs select by class name.

Answer


<!DOCTYPE html>
<html>
<head>
<script type='text/javascript'
  src='http://ajax.googleapis.com/ajax/libs/jquery/1.7.2/jquery.min.js'></script>
<script type='text/javascript'>
$(window).load(function(){<!--from   ww w . j  a  v a 2s.  c o m-->
    $('#test').text('newtext');
    $('.test').text('newtest');
});
</script>
</head>
<body>
  <div id="test">test</div>
  <div id="test">test</div>
  <div class="test">test</div>
  <div class="test">test</div>
</body>
</html>

The code above is rendered as follows: