<!DOCTYPE html>
<html>
<head>
<script type='text/javascript'
src='http://code.jquery.com/jquery-1.10.1.js'></script>
<script type='text/javascript'>
$(window).load(function(){
var addedElement = $('<span>HelloWorld</span>');
addedElement.css('color', 'Red').css('font-weight', 'bold');
$("#box").append(addedElement);
});
</script>
</head>
<body>
<div id="box">existing text:</div>
</body>
</html>