why enableHermes: false but global.HermesInternal = {}?

Question

in android\app\build.gradle:

project.ext.react = [
    entryFile: "index.js",
    enableHermes: false,
]

in index.js

console.log('hermes -> ishermes', global.HermesInternal !== null);

npm run android

in log:

    Time    Tag Message
    18:28:15.576    ReactNativeJS   'hermes -> ishermes', true

why enableHermes: false but global.HermesInternal = {} ??

react-native: 0.61.5

Emulator

Answer 1

JavaScript differentiates between null and undefined.

If Hermes is disabled, then HermesInternal will be undefined. It will not be null.

To check if Hermes is enabled, you can use:

if (typeof(HermesInternal) === "undefined") {
  console.log("Hermes is not enabled");
} else {
  console.log("Hermes is enabled");
}