Hermes for Expo

  1. SDK Version: 40
  2. Platforms(Android/iOS/web/all): Android I guess

I got a new notice using SDK 40:

:bulb: JavaScript bundle sizes effect startup time. Learn more: fyi/ at main 路 expo/fyi 路 GitHub

But I can only find React Native specific information about. how to put it into effect, and no Expo documentation.

Is it available for Expo?


Hermes is not yet available in the managed workflow. See the feature request.

What you can do in the managed workflow is the last paragraph on the page you linked to:

You can analyze the contents of your JavaScript bundles using react-native-bundle-visualizer. It will show you how much each package in your project contributes to the overall bundle size.

See also the following: fyi/ at main 路 expo/fyi 路 GitHub


So no precompiling yet?

Right. Unless you eject to the bare workflow:

You can improve startup time on low-end Android devices in the bare workflow by opting in to using Hermes and precompiling your app to Hermes bytecode at buildtime.

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