Function invokeGuardedCallbackDev

code/communication/public/app.js:1776–1858

(name, func, context, a, b, c, d, e, f)

    var fakeNode = document.createElement('react');

    var invokeGuardedCallbackDev = function (name, func, context, a, b, c, d, e, f) {
      // If document doesn't exist we know for sure we will crash in this method
      // when we call document.createEvent(). However this can cause confusing
      // errors: https://github.com/facebookincubator/create-react-app/issues/3482
      // So we preemptively throw with a better message instead.
      !(typeof document !== 'undefined') ? invariant(false, 'The `document` global was defined when React was initialized, but is not defined anymore. This can happen in a test environment if a component schedules an update from an asynchronous callback, but the test has already finished running. To solve this, you can either unmount the component at the end of your test (and ensure that any asynchronous operations get canceled in `componentWillUnmount`), or you can change the test itself to be asynchronous.') : void 0;
      var evt = document.createEvent('Event');

      // Keeps track of whether the user-provided callback threw an error. We
      // set this to true at the beginning, then set it to false right after
      // calling the function. If the function errors, `didError` will never be
      // set to false. This strategy works even if the browser is flaky and
      // fails to call our global error handler, because it doesn't rely on
      // the error event at all.
      var didError = true;

      // Create an event handler for our fake event. We will synchronously
      // dispatch our fake event using `dispatchEvent`. Inside the handler, we
      // call the user-provided callback.
      var funcArgs = Array.prototype.slice.call(arguments, 3);
      function callCallback() {
        // We immediately remove the callback from event listeners so that
        // nested `invokeGuardedCallback` calls do not clash. Otherwise, a
        // nested call would trigger the fake event handlers of any call higher
        // in the stack.
        fakeNode.removeEventListener(evtType, callCallback, false);
        func.apply(context, funcArgs);
        didError = false;
      }

      // Create a global error event handler. We use this to capture the value
      // that was thrown. It's possible that this error handler will fire more
      // than once; for example, if non-React code also calls `dispatchEvent`
      // and a handler for that event throws. We should be resilient to most of
      // those cases. Even if our error event handler fires more than once, the
      // last error event is always used. If the callback actually does error,
      // we know that the last error event is the correct one, because it's not
      // possible for anything else to have happened in between our callback
      // erroring and the code that follows the `dispatchEvent` call below. If
      // the callback doesn't error, but the error event was fired, we know to
      // ignore it because `didError` will be false, as described above.
      var error = void 0;
      // Use this to track whether the error event is ever called.
      var didSetError = false;
      var isCrossOriginError = false;

      function onError(event) {
        error = event.error;
        didSetError = true;
        if (error === null && event.colno === 0 && event.lineno === 0) {
          isCrossOriginError = true;
        }
      }

      // Create a fake event type.
      var evtType = 'react-' + (name ? name : 'invokeguardedcallback');

      // Attach our event handlers