init (graduate from prototype)

packages/scheduler/src/index.ts

@@ -0,0 +1,40 @@
+const queue: Array<() => void> = []
+const postFlushCbs: Array<() => void> = []
+const p = Promise.resolve()
+let flushing = false
+
+export function nextTick(fn: () => void) {
+  p.then(fn)
+}
+
+export function queueJob(job: () => void, postFlushCb?: () => void) {
+  if (queue.indexOf(job) === -1) {
+    if (flushing) {
+      job()
+    } else {
+      queue.push(job)
+    }
+  }
+  if (postFlushCb) {
+    queuePostFlushCb(postFlushCb)
+  }
+  if (!flushing) {
+    nextTick(flushJobs)
+  }
+}
+
+export function queuePostFlushCb(cb: () => void) {
+  postFlushCbs.push(cb)
+}
+
+export function flushJobs() {
+  flushing = true
+  let job
+  while ((job = queue.shift())) {
+    job()
+  }
+  while ((job = postFlushCbs.shift())) {
+    job()
+  }
+  flushing = false
+}