What kind of architecture is used to judge in the browser?

I think that all processing is completed in the browser. What kind of architecture is used to judge whether the answer is correct or not?
(docker? cypress? jtest?)

You can see the github repo with all the code here GitHub - freeCodeCamp/freeCodeCamp: freeCodeCamp.org's open-source codebase and curriculum. Learn to code for free.

There is also lots of info in the contributing guidelines: Contribution Guidelines | freeCodeCamp.org