The JavaScript runner of this site: frame.js, page-frame.js, worker.js and learntest.js are the site's own code;
learnrun.js is the site's runMain() helper for running the checks with Node.js on your own computer.

acorn-8.18.0.mjs is acorn 8.18.0, unmodified (dist/acorn.mjs of the npm package "acorn").
Licence: MIT, see LICENSE-acorn.txt.
Source: https://github.com/acornjs/acorn/tree/8.18.0