Function DetermineComponentFrameRoot

packages/shared/ReactComponentStackFrame.js:123–184

()

     */
    const RunInRootFrame = {
      DetermineComponentFrameRoot(): [?string, ?string] {
        let control;
        try {
          // This should throw.
          if (construct) {
            // Something should be setting the props in the constructor.
            const Fake = function () {
              throw Error();
            };
            // $FlowFixMe[prop-missing]
            Object.defineProperty(Fake.prototype, 'props', {
              set: function () {
                // We use a throwing setter instead of frozen or non-writable props
                // because that won't throw in a non-strict mode function.
                throw Error();
              },
            });
            if (typeof Reflect === 'object' && Reflect.construct) {
              // We construct a different control for this case to include any extra
              // frames added by the construct call.
              try {
                Reflect.construct(Fake, []);
              } catch (x) {
                control = x;
              }
              Reflect.construct(fn, [], Fake);
            } else {
              try {
                Fake.call();
              } catch (x) {
                control = x;
              }
              // $FlowFixMe[prop-missing] found when upgrading Flow
              fn.call(Fake.prototype);
            }
          } else {
            try {
              throw Error();
            } catch (x) {
              control = x;
            }
            // TODO(luna): This will currently only throw if the function component
            // tries to access React/ReactDOM/props. We should probably make this throw
            // in simple components too
            const maybePromise = fn();

            // If the function component returns a promise, it's likely an async
            // component, which we don't yet support. Attach a noop catch handler to
            // silence the error.
            // TODO: Implement component stacks for async client components?
            if (maybePromise && typeof maybePromise.catch === 'function') {
              maybePromise.catch(() => {});
            }
          }
        } catch (sample) {
          // This is inlined manually because closure doesn't do it for us.
          if (sample && control && typeof sample.stack === 'string') {
            return [sample.stack, control.stack];