gecko-dev/dom/workers/test/test_navigator_iframe.js

var worker = new Worker("navigator_worker.js");

var is = window.parent.is;
var ok = window.parent.ok;
var SimpleTest = window.parent.SimpleTest;

worker.onmessage = function(event) {
  var args = JSON.parse(event.data);

  if (args.name == "testFinished") {
    SimpleTest.finish();
    return;
  }

  if (typeof navigator[args.name] == "undefined") {
    ok(false, "Navigator has no '" + args.name + "' property!");
    return;
  }

  if (args.name === "languages") {
    is(
      navigator.languages.toString(),
      args.value.toString(),
      "languages matches"
    );
    return;
  }

  if (args.name === "storage") {
    is(typeof navigator.storage, typeof args.value, "storage type matches");
    return;
  }

  if (args.name === "connection") {
    is(
      typeof navigator.connection,
      typeof args.value,
      "connection type matches"
    );
    return;
  }

  if (args.name === "mediaCapabilities") {
    is(
      typeof navigator.mediaCapabilities,
      typeof args.value,
      "mediaCapabilities type matches"
    );
    return;
  }

  if (args.name === "gpu") {
    is(typeof navigator.gpu, typeof args.value, "gpu type matches");
    return;
  }

  is(
    navigator[args.name],
    args.value,
    "Mismatched navigator string for " + args.name + "!"
  );
};

worker.onerror = function(event) {
  ok(false, "Worker had an error: " + event.message);
  SimpleTest.finish();
};

var { AppConstants } = SpecialPowers.Cu.import(
  "resource://gre/modules/AppConstants.jsm",
  {}
);
var isNightly = AppConstants.NIGHTLY_BUILD;
var isRelease = AppConstants.RELEASE_OR_BETA;

worker.postMessage({ isNightly, isRelease });