Website Feedback / Feedback Button / Embedded Data with JavaScript variables

Hello,
We have a stand alone app which we embed on some of our partners' websites.
We created a site intercept to get feedback on users' experience (feedback button + survey).
In embedded data creation, I need to be able to differentiate the data by partner. However all our pages have all the same URL (not variable), so I cannot create embedded data from URL. Support team kindly suggested we use Javascript variables.
My question is : where do we write the variables ? On the web page, or is it possible to add them on the snippet code extracted from Intercept Deployment from Qualtrics?
Can you provide an example?
Thanks for your help.

Marc