Electron.js / jQuery UI - Uncaught ReferenceError: jQuery is not defined

I found the problem. Turns out that jQuery thinks it is in an enviroment without a window with a DOM.

From jQuery.js line 17:

    if ( typeof module === "object" && typeof module.exports === "object" ) {


    // For CommonJS and CommonJS-like environments where a proper `window`
    // is present, execute the factory and get jQuery.
    // For environments that do not have a `window` with a `document`
    // (such as Node.js), expose a factory as module.exports.
    // This accentuates the need for the creation of a real `window`.
    // e.g. var jQuery = require("jquery")(window);
    // See ticket #14549 for more info.


    module.exports = global.document ?
        factory( global, true ) :
        function( w ) {
            if ( !w.document ) {
                throw new Error( "jQuery requires a window with a document" );
            }
            return factory( w );
        };
} else {
    factory( global );
}

Ghettofix solution:

Remove the entire 'if sentence' and keep only this: factory( global );

I am not sure why this happend but my best guess is that the Electron app, which both have a front-end with DOM and a backend without DOM, the jQuery chose the backend.