如果不加载Jquery，则检查Jquery是否存在

Posted 2021-02-25

If you are working on apps development to adapt on different sites that you don't have access to them, and need to load Jquery, but don't wanna load it twice this will help you !

if (typeof jQuery == 'undefined') {  
    <script type="text/javascript" src="http://www.google.com/jsapi"></script>
    <script type="text/javascript">
    google.load("jquery", "1.4.2");
    </script>
}