jquery基本选择器标签名选择器

<!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>
  <title> new document </title>
  <meta http-equiv="Content-Type" content="text/html;charset=UTF-8" />

  <style type="text/css"></style>
  <script  type="text/javascript" src="jquery-1.7.1.min.js"></script>
  <script type="text/javascript">
        window.onload=function(){
            document.getElementById(\'btnOk\').onclick=function(){
                $(\'div\').html(\'php\');
            };
        };
  </script>
 </head>
 <body>
  <div id="div1">div1</div>
  <hr/>
  <div>div2</div>
    <hr/>
  <input type="button" id=\'btnOk\' value=\'确定\'  />
 </body>
</html>

详细解释：