<html>
<head>
<script src="https://libs.baidu.com/jquery/1.10.2/jquery.min.js">
</script>
<script>
$(document).ready(function(){
$("button").click(function(){
$("div").contents().filter("em").wrap("<b/>");
});
});
</script>
</head>
<body>
<div><em>Hello world! What a beautiful day!</em></div>
<p>In this example, by clicking on the button, we search for all the text nodes inside the div element and wrap them with a b element.</p>
<button>Find all text nodes in div and wrap them</button><br>
</body>
</html>