Get list of all global variables on a website

script.js

Object.keys(window).filter(
  (x) =>
    typeof window[x] !== "function" &&
    Object.entries(Object.getOwnPropertyDescriptor(window, x)).filter(
      (entry) =>
        ["value", "writable", "enumerable", "configurable"].includes(entry[0]) &&
        entry[1]
    ).length === 4
);

source: https://stackoverflow.com/a/52693392