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.

先檢視文件中關於 effects 會在新的 renders 之前被 flush 的引述，接著將其措辭與兩個 ReactDOM.render 呼叫位置，以及 concurrent 和 non-concurrent 的行為進行比較。完成的標準是文件清楚說明受支援的保證，並釐清該保證是一般適用於 renders，還是只適用於 effect 的順序。