如果是字符串的话
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>无标题文档</title>
</head>
<body>
<script type="text/javascript">
var str = '<h1 id="rname"> <a href="http://blog.sina.com/uservalue"> 帅哥的博客 </a> </h1> ';
var reg = /<a.*?\/(\w+)"/;
alert( reg.exec(str)[1] );
</script>
</body>
</html>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>无标题文档</title>
</head>
<body>
<script type="text/javascript">
var str = '<h1 id="rname"> <a href="http://blog.sina.com/uservalue"> 帅哥的博客 </a> </h1> ';
var reg = /<a.*?\/(\w+)"/;
alert( reg.exec(str)[1] );
</script>
</body>
</html>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>无标题文档</title>
</head>
<body>
<h1 id="rname">
<a href="http://blog.sina.com/uservalue"> 帅哥的博客 </a>
</h1>
<script type="text/javascript">
var href = document.getElementById("rname").getElementsByTagName("a")[0].href;
var reg = /\/(\w+)$/;
alert( reg.exec(href)[1] );
</script>
</body>
</html>