chromium/content/test/data/dom_storage/verify_session_storage_data.html

<!DOCTYPE html>
<meta charset=utf-8>
<script src="common.js"></script>
<script>
function test() {
  let val = window.sessionStorage['foo'];
  if (val !== 'bar')
    fail('Read incorrect value from sessionStorage. Expected "bar", got "' + val + '"');
  else
    done();
}
</script>
<body onload="setTimeout(test, 0)">
<div id="status">Starting...<br/></div>