Run IO as synchronously as possible

japgolly · japgolly · commit 6adbb22bde5b · 2022-01-21T12:24:40.000+11:00
Closes #1010
diff --git a/coreExtCatsEffect/src/main/scala/japgolly/scalajs/react/util/EffectCatsEffect.scala b/coreExtCatsEffect/src/main/scala/japgolly/scalajs/react/util/EffectCatsEffect.scala
@@ -99,7 +99,7 @@ object EffectCatsEffect {
       f => () => fa.unsafeRunAsync(ea => f(ea.toTry)())(runtime())
 
     override def dispatch[A](fa: IO[A]): Unit =
-      fa.unsafeRunAndForget()(runtime())
+      fa.syncStep.unsafeRunSync().fold(_.unsafeRunAndForget()(runtime()), _ => ())
   }
 
   private lazy val tryUnit: Try[Unit] =
diff --git a/doc/changelog/2.0.1.md b/doc/changelog/2.0.1.md
@@ -3,3 +3,4 @@
 ### Bug fixes
 
 * Fix infinite loop in functional components with reuse + `Reusability.never` ([#1027](https://github.com/japgolly/scalajs-react/issues/1027))
+* When using `cats.effect.IO` as event handlers, it runs as synchronously as possible until it runs into an async step.

Original file line number	Diff line number	Diff line change
`@@ -99,7 +99,7 @@ object EffectCatsEffect {`
`99`	`99`	`f => () => fa.unsafeRunAsync(ea => f(ea.toTry)())(runtime())`
`100`	`100`
`101`	`101`	`override def dispatch[A](fa: IO[A]): Unit =`
`102`		`- fa.unsafeRunAndForget()(runtime())`
	`102`	`+ fa.syncStep.unsafeRunSync().fold(_.unsafeRunAndForget()(runtime()), _ => ())`
`103`	`103`	`}`
`104`	`104`
`105`	`105`	`private lazy val tryUnit: Try[Unit] =`
Original file line number	Diff line number	Diff line change
`@@ -3,3 +3,4 @@`
`3`	`3`	`### Bug fixes`
`4`	`4`
`5`	`5`	* Fix infinite loop in functional components with reuse + `Reusability.never` ([#1027](https://github.com/japgolly/scalajs-react/issues/1027))
	`6`	+* When using `cats.effect.IO` as event handlers, it runs as synchronously as possible until it runs into an async step.