gecko-dev/dom/network/tests/worker_network_basics.js

function ok(a, msg) {
  postMessage({type: 'status', status: !!a, msg: msg});
}

function is(a, b, msg) {
  ok(a === b, msg);
}

function finish() {
  postMessage({type: 'finish'});
}

ok('connection' in navigator, "navigator.connection should exist");

ok(navigator.connection, "navigator.connection returns an object");

ok(navigator.connection instanceof EventTarget,
   "navigator.connection is a EventTarget object");

ok('type' in navigator.connection,
   "type should be a Connection attribute");
is(navigator.connection.type, "none",
   "By default connection.type equals to none");
finish();