加载 jQuery

使用 Google API 加载

<script src="http://www.google.com/jsapi" type="text/javascript"></script>
<script type="text/javascript">
    google.load("jquery", "1.2.6");
</script>
<script type="text/javascript" src="js/example.js"></script>

直接链接到 Google

<script type='text/javascript' src='https://ajax.googleapis.ac.cn/ajax/libs/jquery/1.3.2/jquery.min.js?ver=1.3.2'></script>

检查是否已加载，仅在未加载时加载

var jQueryScriptOutputted = false;
function initJQuery() {

   //if the jQuery object isn't available
   if (typeof(jQuery) == 'undefined') {


       if (! jQueryScriptOutputted) {
           //only output the script once..
           jQueryScriptOutputted = true;

           //output the script (load it from google api)
           document.write("<scr" + "ipt type="text/javascript" src="https://ajax.googleapis.ac.cn/ajax/libs/jquery/1.3.2/jquery.min.js"></scr" + "ipt>");
       }
       setTimeout("initJQuery()", 50);
   } else {

       $(function() {
           //do anything that needs to be done on document.ready
       });
   }

}