When does compilation into bytecode happen exactly?

[IslamRustamov]

So, let’s imagine that we are building Android app with React Native and Hermes enabled.
We know that Hermes compiles JS into bytecode, but when it happens exactly? When we build an APK, or when user installs this APK?

[ecreeth]

This happens at build time. You can learn more about it React Native EU 2019: Tzvetan Mikov - Improving React Native Performance

[ecreeth]

Yes. The bytecode cannot be viewed as plain text.

[IslamRustam]

Alright. Thanks!

Just the last 2 questions:

1. Does it mean that using Hermes is more secure than JSC? I mean, is there any way we can "debug" this bytecode/do something with it? (not that we could understand much from minified JS from JSC bundling, but still)
2. Probably a silly question, is there any way to "view" the bytecode? For example, we can view photo if it's in base64 format.

[ecreeth]

You can "read" a decompiled version of the bytecode with hbctool or other tools like that. It doesn't mean it's more secure, it is just more difficult to read.

[IslamRustam]

Alright, thanks for that!

[tmikov]

also hermes -dump-bytecode file.hbc