Don't use closures in DevTools injection #18278
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React Core Team
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Details of bundled changes.Comparing: 5474a83...0c43f3e react-art
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ReactDOM: size: 0.0%, gzip: -0.0% Size changes (experimental) |
Details of bundled changes.Comparing: 5474a83...0c43f3e react-art
react-test-renderer
react-native-renderer
react-dom
react-reconciler
Size changes (stable) |
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Looks like fast-refresh is mutating the hook object. :( |
bvaughn
approved these changes
Mar 11, 2020
| if ( | ||
| injectedHook && | ||
| typeof injectedHook.onScheduleFiberRoot === 'function' | ||
| ) { |
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Could sent pointers to e.g. onScheduleFiberRoot directly so we wouldn't have to do the property access
if (typeof onScheduleFiberRoot === 'function') {
onScheduleFiberRoot(rendererID, root, chilren);
}
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I think Seb is saying that property gets mutated by Fast Refresh. (I don't actually remember if it does but I guess?)
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So, landing this? |
Nested closures are tricky. They're not super efficient and when they share scope between multiple closures they're hard for a compiler to optimize. It's also unclear how many versions will be created. By hoisting things out an just make it simple calls the compiler can do a much better job.
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Thanks for this change. FYI - It is also fixing a bug with React Fast refresh which happen when In our setup, we have 2 bundles - one contains React (loaded first) and a second one containing the Fast Refresh runtime (+ app code). Since Fast refresh runtime is executed after React it wasn't working fully. Beside this little quirk Fast Refresh is really great and reliable:+1: |
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Nested closures are tricky. They're not super efficient and when they share scope between multiple closures they're hard for a compiler to optimize. It's also unclear how many versions will be created.
By hoisting things out an just make it simple calls the compiler can do a much better job.
Before
After
Note that it's still sub-optimal because the config object gets created even though it should be able to be inlined by Closure Compiler. We should really switch this per-renderer config object to be a HostConfig the whole thing instead to avoid that.
The injected object is also created outside the condition so it's always created even if no devtools is present.