A JavaScript engine optimized for running React Native
...It won't weigh your app down. It's simple to get started with Hermes in React Native apps. Hermes is open source and implements JavaScript standards. You will now be in a directory with the output of building Hermes into CLI tools. From here you can run a piece of JavaScript. If you have an existing app based on an earlier version of React Native, you will have to upgrade it first. Each Hermes release is aimed at a specific RN version. The rule of thumb is to always follow Hermes releases strictly. Version mismatch can result in instant crash of your apps in the worst case scenario. ...