feat(schedule): scheduler uses macroTasks when possible

src/schedule.ts

@@ -1,30 +1,42 @@
 import { IFiber, ITask, ITaskCallback } from "./type"
-import { options } from "./reconcile"
 
 const queue: ITask[] = []
 const threshold: number = 1000 / 60
 const transitions = []
 let deadline: number = 0
 
 export const startTransition = (cb) => {
-  transitions.push(cb) && postMessage()
+  transitions.push(cb) && runTransition()
 }
 
 export const schedule = (callback: any): void => {
   queue.push({ callback } as any)
   startTransition(flush)
 }
 
-const postMessage = (() => {
+const transitionRunnerFactory = (useMicrotasks: boolean) => {
   const cb = () => transitions.splice(0, 1).forEach((c) => c())
 
+  if (useMicrotasks) {
+    if (typeof queueMicrotask !== "undefined") {
+      return () => queueMicrotask(cb)
+    }
+    const resolvedPromise = Promise.resolve()
+    return () => resolvedPromise.then(cb)
+ }
+
   if (typeof MessageChannel !== "undefined") {
     const { port1, port2 } = new MessageChannel()
     port1.onmessage = cb
     return () => port2.postMessage(null)
   }
   return () => setTimeout(cb)
-})()
+}
+
+const runTransitionAsTask = transitionRunnerFactory(false)
+const runTransitionAsMicroTask = transitionRunnerFactory(true)
+
+let runTransition = runTransitionAsMicroTask
 
 const flush = (): void => {
   deadline = getTime() + threshold
@@ -44,10 +56,10 @@ const flush = (): void => {
 }
 
 export const shouldYield = (): boolean => {
-  if (options.sync) return false
-  return (
+  const isInputPending =
     (navigator as any)?.scheduling?.isInputPending() || getTime() >= deadline
-  )
+  runTransition = isInputPending ? runTransitionAsTask : runTransitionAsMicroTask
+  return isInputPending
 }
 
 export const getTime = () => performance.now()