Add .dispatch to {,Async}Callback

Closes #948

Author: japgolly

callback/src/main/scala-2/japgolly/scalajs/react/callback/AsyncCallback.scala

@@ -1092,6 +1092,13 @@ final class AsyncCallback[+A] private[AsyncCallback] (val underlyingRepr: AsyncC
   def fork_ : Callback =
     delayMs(1).toCallback
 
+  /** Runs this async computation in the background.
+    *
+    * Unlike [[fork_]] this returns an `AsyncCallback[Unit]` instead of a `Callback`.
+    */
+  def dispatch: AsyncCallback[Unit] =
+    delayMs(1).void
+
   /** Record the duration of this callback's execution. */
   def withDuration[B](f: (A, FiniteDuration) => AsyncCallback[B]): AsyncCallback[B] = {
     val nowMS: AsyncCallback[Long] = CallbackTo.currentTimeMillis.asAsyncCallback

callback/src/main/scala-2/japgolly/scalajs/react/callback/CallbackTo.scala

@@ -695,6 +695,10 @@ final class CallbackTo[+A] private[react] (private[CallbackTo] val trampoline: T
     }
   }
 
+  /** Runs this computation in the background. */
+  def dispatch: Callback =
+    asAsyncCallback.fork_
+
   def withFilter(f: A => Boolean): CallbackTo[A] =
     map[A](a => if (f(a)) a else
       // This is what scala.Future does

callback/src/main/scala-3/japgolly/scalajs/react/callback/AsyncCallback.scala

@@ -1096,6 +1096,13 @@ final class AsyncCallback[+A] private[AsyncCallback] (val underlyingRepr: AsyncC
   inline def fork_ : Callback =
     delayMs(1).toCallback
 
+  /** Runs this async computation in the background.
+    *
+    * Unlike [[fork_]] this returns an `AsyncCallback[Unit]` instead of a `Callback`.
+    */
+  def dispatch: AsyncCallback[Unit] =
+    delayMs(1).void
+
   /** Record the duration of this callback's execution. */
   def withDuration[B](f: (A, FiniteDuration) => AsyncCallback[B]): AsyncCallback[B] = {
     val nowMS: AsyncCallback[Long] = CallbackTo.currentTimeMillis.asAsyncCallback

callback/src/main/scala-3/japgolly/scalajs/react/callback/CallbackTo.scala

@@ -722,6 +722,10 @@ final class CallbackTo[+A] /*private[react]*/ (private[CallbackTo] val trampolin
     }
   }
 
+  /** Runs this computation in the background. */
+  def dispatch: Callback =
+    asAsyncCallback.fork_
+
   def withFilter(f: A => Boolean): CallbackTo[A] =
     map[A](a => if f(a) then a else
       // This is what scala.Future does

doc/changelog/2.0.0.md

@@ -339,7 +339,9 @@ You can run the script in the Migration section at the bottom of the page to aut
     *(e.g. `renderBackend[Backend[X]]` where `X` is a type already in scope)*
   * Support `CallbackOption[Unit]` being passed directly to event handling vdom
 
-* `TriStateCheckbox` now accepts an optional `Reusable[TagMod]` in its `Props` that will be applied to the `<input>`
+* Additions:
+  * `TriStateCheckbox` now accepts an optional `Reusable[TagMod]` in its `Props` that will be applied to the `<input>`
+  * Add `.dispatch` to `Callback` and `AsyncCallback` which schedules (-and-forgets) the callback to be run in the background
 
 * Upgrade deps
   * Cats-effect to 3.2.2