$ is not a function jQuery error after upgrade from 7 to 8.0

So I've upgraded from 7 to 8.0 and I got this error in a custom web part:

`Uncaught TypeError: $ is not a function`

on the line

`var $=jQuery.noConflict();$(function(){$(".footable").footable()})`

stacktrace looks like this:

(anonymous function)    @GetResource.ashx?scriptfile=%2fCMSScripts%2fCustom%2fCSOBL%2fstartFoo.js:1
v   @GetResource.ashx?scriptfile=~%2fCMSScripts%2fjquery%2fjquery-core.js:16
fireWith    @GetResource.ashx?scriptfile=~%2fCMSScripts%2fjquery%2fjquery-core.js:16
ready   @GetResource.ashx?scriptfile=~%2fCMSScripts%2fjquery%2fjquery-core.js:16
u   @GetResource.ashx?scriptfile=~%2fCMSScripts%2fjquery%2fjquery-core.js:16

Can you recommend any solution to this?

I already tried

ScriptHelper.RegisterJQuery(Page);
ScriptHelper.RegisterJQueryUI(Page);
ScriptHelper.RegisterJQueryDialog(Page);

or

`ScriptHelper.RegisterJQuery(Page);`