monkeypatch.ts

function monkeyPatchXMLHttpRequest() {
  const { xhook } = require("xhook");

  xhook.before(function (request) {
    if (request.headers[ "X-Passphrase" ]) {
      request.passphrase = request.headers[ "X-Passphrase" ];
      delete request.headers[ "X-Passphrase" ];
    }
  });

  xhook.after(async function (request, response, callback) {
    if (request.passphrase) {
      try {
        const plaintext = await Fernet.decrypt(request.passphrase, atob(response.text));
        response.text = response.data = plaintext;
      } catch (e) {
        response.text = e.message;
        response.status = 400;
        response.statusText = e.message;
      }
    }

    callback();
  });
}