From 25a547a359a4cdb9fde83723497b75c99c11a5cc Mon Sep 17 00:00:00 2001
From: Adam Bradley <adamdbradley@users.noreply.github.com>
Date: Thu, 27 Aug 2020 20:36:47 -0500
Subject: [PATCH] fix(prerender): hAsync only returns promise if it has to

---
 src/hydrate/platform/h-async.ts | 27 +++++++++++--
 src/mock-doc/window.ts          | 68 +++++++++++++++++++--------------
 2 files changed, 63 insertions(+), 32 deletions(-)

diff --git a/src/hydrate/platform/h-async.ts b/src/hydrate/platform/h-async.ts
index 5320023ce32..ed99749ee44 100644
--- a/src/hydrate/platform/h-async.ts
+++ b/src/hydrate/platform/h-async.ts
@@ -1,9 +1,28 @@
 import * as d from '../../declarations';
 import { h } from '@runtime';
+import { isPromise } from '@utils';
+import { consoleDevError } from '@platform';
 
-export const hAsync = async (nodeName: any, vnodeData: any, ...children: d.ChildType[]) => {
-  if (children) {
-    children = await Promise.all(children);
+export const hAsync = (nodeName: any, vnodeData: any, ...children: d.ChildType[]) => {
+  if (Array.isArray(children) && children.length > 0) {
+    // only return a promise if we have to
+    if (children.some(isPromise)) {
+      // has children and at least one of them is async
+      // wait on all of them to be resolved
+      return Promise.all(children)
+        .then(resolvedChildren => {
+          return h(nodeName, vnodeData, ...resolvedChildren);
+        })
+        .catch(err => {
+          consoleDevError(err);
+          return h(nodeName, vnodeData);
+        });
+    }
+
+    // no async children, return sync
+    return h(nodeName, vnodeData, ...children);
   }
-  return h(nodeName, vnodeData, ...children);
+
+  // no children, return sync
+  return h(nodeName, vnodeData);
 };
diff --git a/src/mock-doc/window.ts b/src/mock-doc/window.ts
index a6acb0f5d21..fd0952914c6 100644
--- a/src/mock-doc/window.ts
+++ b/src/mock-doc/window.ts
@@ -423,39 +423,47 @@ export class MockWindow {
 
     if (this.__allowInterval) {
       const intervalId = this.__setInterval(() => {
-        this.__timeouts.delete(intervalId);
-
-        try {
-          callback(...args);
-        } catch (e) {
-          if (this.console) {
-            this.console.error(e);
-          } else {
-            console.error(e);
+        if (this.__timeouts) {
+          this.__timeouts.delete(intervalId);
+
+          try {
+            callback(...args);
+          } catch (e) {
+            if (this.console) {
+              this.console.error(e);
+            } else {
+              console.error(e);
+            }
           }
         }
       }, ms) as any;
 
-      this.__timeouts.add(intervalId);
+      if (this.__timeouts) {
+        this.__timeouts.add(intervalId);
+      }
 
       return intervalId;
     }
 
     const timeoutId = this.__setTimeout(() => {
-      this.__timeouts.delete(timeoutId);
+      if (this.__timeouts) {
+        this.__timeouts.delete(timeoutId);
 
-      try {
-        callback(...args);
-      } catch (e) {
-        if (this.console) {
-          this.console.error(e);
-        } else {
-          console.error(e);
+        try {
+          callback(...args);
+        } catch (e) {
+          if (this.console) {
+            this.console.error(e);
+          } else {
+            console.error(e);
+          }
         }
       }
     }, ms) as any;
 
-    this.__timeouts.add(timeoutId);
+    if (this.__timeouts) {
+      this.__timeouts.add(timeoutId);
+    }
 
     return timeoutId;
   }
@@ -468,20 +476,24 @@ export class MockWindow {
     ms = Math.min(ms, this.__maxTimeout);
 
     const timeoutId = (this.__setTimeout(() => {
-      this.__timeouts.delete(timeoutId);
+      if (this.__timeouts) {
+        this.__timeouts.delete(timeoutId);
 
-      try {
-        callback(...args);
-      } catch (e) {
-        if (this.console) {
-          this.console.error(e);
-        } else {
-          console.error(e);
+        try {
+          callback(...args);
+        } catch (e) {
+          if (this.console) {
+            this.console.error(e);
+          } else {
+            console.error(e);
+          }
         }
       }
     }, ms) as any) as number;
 
-    this.__timeouts.add(timeoutId);
+    if (this.__timeouts) {
+      this.__timeouts.add(timeoutId);
+    }
 
     return timeoutId;
   }