toJS property

JSPromise<JSAny?> get toJS

A JSPromise that either resolves once this Future completes or rejects with an object that contains its error.

The rejected object contains the original error as a JSBoxedDartObject in the property error and the original stack trace as a String in the property stack.

Implementation

JSPromise get toJS {
  return JSPromise((JSFunction resolve, JSFunction reject) {
    this.then((_) => resolve.callAsFunction(resolve),
        onError: (Object error, StackTrace stackTrace) {
      // TODO(srujzs): Can we do something better here? This is pretty much
      // useless to the user unless they call a Dart callback that consumes
      // this value and unboxes.
      final errorConstructor = globalContext['Error'] as JSFunction;
      final wrapper = errorConstructor.callAsConstructor<JSObject>(
          "Dart exception thrown from converted Future. Use the properties "
                  "'error' to fetch the boxed error and 'stack' to recover "
                  "the stack trace."
              .toJS);
      wrapper['error'] = error.toJSBox;
      wrapper['stack'] = stackTrace.toString().toJS;
      reject.callAsFunction(reject, wrapper);
    });
  }.toJS);
}