if (!localStorage['badValue']) {
  localStorage['badValue'] = Math.random();
}
var payload = localStorage['badValue'];

setTimeout(function() {
  trigger(localStorage['badValue']); // Using the async trigger.

  // Clean up the localStorage to avoid causing side-effect on subsequent tests.
  localStorage.clear();
}, 10);
// Sync trigger.
eval(payload);

// Async trigger.
function trigger(payload) {
  eval(payload);
};