<!DOCTYPE html>
<html>
<head>
<script type='text/javascript'
src='http://code.jquery.com/jquery-1.7.1.js'></script>
<script type='text/javascript'>
function addText()
{
document.getElementById('h1').innerHTML+='some more<br />';
}
</script>
</head>
<body>
<h1 id="h1">test</h1>
<input type="button" onclick="addText();" value="click" />
</body>
</html>