var worker = new Worker('./worker.js');

var id = 'Promise.resolve()';

worker.addEventListener('message', function(event) {
  var data = event.data;
  if (!data.success) {
    alert(data.id + ' failed: ' + data.message);
  } else {
    alert(data.id + ' worked');
  }
});

worker.postMessage({id: id});