在移动设备上，当我访问我的网站时，菜单在所有页面中都能正常运行。
一旦我点击浏览器＆＃39;返回＆＃39;按钮并返回上一页我的移动菜单不再工作，看到以下错误：
mediaelement-and-player.min.js:3 Uncaught TypeError: Cannot read property 'extend' of undefined
at mediaelement-and-player.min.js:3
at mediaelement-and-player.min.js:3
(anonymous) @ mediaelement-and-player.min.js:3
(anonymous) @ mediaelement-and-player.min.js:3
kontakt.html:883 Uncaught ReferenceError: jQuery is not defined
at kontakt.html:883
(anonymous) @ kontakt.html:883
kontakt.html:887 Uncaught ReferenceError: $ is not defined
at kontakt.html:887
(anonymous) @ kontakt.html:887
kontakt.html:912 Uncaught ReferenceError: $ is not defined
at kontakt.html:912
(anonymous) @ kontakt.html:912
任何人都有任何线索吗？