Does React Native compile JavaScript into Java for Android?

javascript java android react-native react-native-android
unlimited101 picture unlimited101 · Dec 13, 2016 · Viewed 27.7k times · Source

When I develop hybrid apps with React Native. Does the JavaScript code I write transform into Java-Code or Java-Bytecode for the Dalvik/ART Runtime when I create an Android-App from my React Native code? Or are just the UI components compiled into native UI components? Or does a library like the Fetch API compile the JavaScript code into Java-Code or Java-Bytecode?

Answer

Marc picture Marc · Dec 13, 2016

Basically, you write Javascript. The Javascript communicates with native components (Java on Android, Objective C on iOS, C# on Windows).

The communication occurs through the so-called "bridge". If at any time you feel that this communication slows things down too much, you can choose to implement the Javascript functionality in Java, Objective C, or C# respectively in order to run purely native. In this case, you are writing directly in native code, so there's no Javascript to native compilation.

This will sacrifice compatibility for performance. Normally, this is not necessary.

  • Further reading

Understanding React Native bridge concept

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