JavaScript实现网页关键字高亮显示

<!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>JS查询替换关键字</title>
<style type="text/css">
span{color:#f00;font-weight:bold;}
</style>
</head>
<body>
<div>我是标题:这里是文字介绍!</div>
<div>我是老二:老二的描述性文字。</div>
<script type="text/javascript">
var divs = document.getElementsByTagName('div');
for(i=0;i<divs.length;i++){
  var text = divs[i].innerHTML;
  var index = text.indexOf(':');
  var span = document.createElement('span');
  span.innerHTML = text.substring(0,index+1);
  divs[i].innerHTML = text.substring(index+1);
  divs[i].insertBefore(span,divs[i].firstChild);
}
</script>
</body>
</html>