How to use “get URL data” variables in configrator-app?

Hello Verge3D-Gurus,
would you please help me get started with puzzles?
I just begin working with Verge3D and I have only a little programming background.
I want to create a simple app that can be used as a blue-print for upcoming larger projects. The task I try to solve: Read the get-params from the URL and use them in my little configurator app.

Lets say, in the scene I have the default cube and 3 materials.
Opening the app with the URL http://localhost:8668/applications/url-test/url-test.html?var1=mat1 is supposed to have the material 1 assigend to the cube, while http://localhost:8668/applications/url-test/url-test.html?var1=mat2 should assign material 2 to the cube.

I have a working puzzle setup that has the functionality, by clicking buttons/objects in the scene to change the material, but I struggle on how to use the get-variables from the URL instead of using the “when clicked” puzzle.

Thank you for any hint and help.
Best regards!