Untitled

<!DOCTYPE html>
<html>
<head>
<meta charset=utf-8 />
<title>test data-*</title>
<script src="data.js"></script>
</head>
<body>
  <p data-id="ok" data-name="remy" data-screen-name="rem" id="hello">Hello World</p>
  <script>
    var el = document.getElementById('hello'), dl = el.dataset, a = [], key;
    for (key in dl) a.push(key + ': ' + dl[key]);
    alert(a.join('\n'));

    a.length = 0;
    el.setAttribute('data-foo', 'bar');
    if (el._datasetCache) alert('Houston: we have a problem!');

    dl = el.dataset;
    for (key in dl) a.push(key + ': ' + dl[key]);
    alert(a.join('\n'));
  </script>
</body>
</html>