Timing of effects

Although useEffect is deferred until after the browser has painted, it's guaranteed to fire before any new renders. React will always flush a previous render's effects before starting a new update.

Is this true in both concurrent and non-concurrent mode. It would appear intuitively that these two call-sites in non-concurrent mode would be deterministic:

ReactDOM.render(<Foo>, container)
ReactDOM.render(<Foo>, container)

That is it would invoke a new render before the effect in the first render has been invoked.

If so would it make more sense to specify it is only in relation to effects i.e previous effects are guaranteed to run before future effects.

As it stands, it looks appears as though the "render" call-site is non-deterministic in non-concurrent.

Commencez par examiner l’affirmation citée de la documentation selon laquelle les effets sont vidés avant les nouveaux rendus, puis comparez sa formulation avec les deux sites d’appel de ReactDOM.render ainsi qu’avec le comportement concurrent et non-concurrent. C’est terminé lorsque la documentation énonce clairement la garantie prise en charge et détermine si elle s’applique aux rendus en général ou uniquement à l’ordre d’exécution des effets.