[Compiler]: Using `for` loop for array of strings

[saul-atomrigs]

What kind of issue is this?

• React Compiler core (the JS output is incorrect, or your app works incorrectly after optimization)
• babel-plugin-react-compiler (build issue installing or using the Babel plugin)
• eslint-plugin-react-compiler (build issue installing or using the eslint plugin)
• react-compiler-healthcheck (build issue installing or using the healthcheck script)

Link to repro

react/compiler/packages/babel-plugin-react-compiler/src/Entrypoint/Program.ts

Line 266 in 9eb288e

for (const prefix in sources) {

Repro steps

Hello @gsathya ,

I was wondering if the for ... in was intended instead of for ... of.

I think for ... of is more recommended for array of strings (Array<string>) like in this case.

Thanks!

How often does this bug happen?

Every time

What version of React are you using?

18.3.1

[gsathya]

I agree for.. of is generally better but this seems fine. Instead of these one-offs, I wonder if we should just simply add a lint rule to simply disallow for.. in in the code base.

[guillaumebrunerie]

But doesn't for ... in iterate over the keys, as opposed to for ... of which iterates over the values? So in this case, prefix will be "0", "1", "2" etc., no matter which strings the array contains.

[poteto]

yeah, this looks like it might be a bug. would either of you like to open a PR to fix?

But doesn't for ... in iterate over the keys, as opposed to for ... of which iterates over the values? So in this case, prefix will be "0", "1", "2" etc., no matter which strings the array contains.