Merge bbaa9a1 into 6454b14

CHANGELOG.md

@@ -1,3 +1,5 @@
+* Another fix for invalid `actionAsync` context when promises resolve at the same time in different actionAsync calls, by [xaviergonz](https://github.com/xaviergonz) through [#244](https://github.com/mobxjs/mobx-utils/pull/244)
+
 # 5.5.5
 
 * Fixed tree-shaking mobx-utils, see [#238](https://github.com/mobxjs/mobx-utils/pull/238) by [IgorBabkin](https://github.com/IgorBabkin)

src/action-async.ts

@@ -16,8 +16,29 @@ interface IActionAsyncContext {
     args: IArguments
 }
 
-let taskOrderPromise = Promise.resolve()
-const emptyFunction = () => Promise.resolve()
+let taskOrderPromise: Promise<any> = Promise.resolve()
+
+let queueMicrotaskPolyfill: typeof queueMicrotask
+
+if (typeof queueMicrotask !== "undefined") {
+    // use real implementation if possible
+    queueMicrotaskPolyfill = queueMicrotask
+} else if (typeof process !== "undefined" && process.nextTick) {
+    // fallback to node's process.nextTick in node <= 10
+    queueMicrotaskPolyfill = (cb: any) => {
+        process.nextTick(cb)
+    }
+} else {
+    // use setTimeout for old browsers
+    queueMicrotaskPolyfill = (cb: any) => {
+        setTimeout(cb, 0)
+    }
+}
+
+const idle = () =>
+    new Promise(r => {
+        queueMicrotaskPolyfill(r)
+    })
 
 const actionAsyncContextStack: IActionAsyncContext[] = []
 
@@ -41,9 +62,7 @@ export async function task<R>(value: R | PromiseLike<R>): Promise<R> {
 
         // we use this trick to force a proper order of execution
         // even for immediately resolved promises
-        // we need to also use catch or else it won't work for older versions of node (< 10)
-        // since it would resolve them immediately
-        taskOrderPromise = taskOrderPromise.then(emptyFunction).catch(emptyFunction)
+        taskOrderPromise = taskOrderPromise.then(idle)
         await taskOrderPromise
 
         return ret