From e0e676366834b44690d0056c70fb0cd474a51ab3 Mon Sep 17 00:00:00 2001
From: nieling1 <52280105+nieling1@users.noreply.github.com>
Date: Mon, 17 Jul 2023 18:06:57 +0800
Subject: [PATCH] =?UTF-8?q?=F0=9F=91=BD=EF=B8=8F=20requestIdleCallback=20a?=
 =?UTF-8?q?dd=20the=20polyfill=20of=20MessageChannel=20(#2475)?=
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---
 src/prefetch.ts | 45 ++++++++++++++++++++++++++++++++-------------
 1 file changed, 32 insertions(+), 13 deletions(-)

diff --git a/src/prefetch.ts b/src/prefetch.ts
index 6af7697..43a42f1 100644
--- a/src/prefetch.ts
+++ b/src/prefetch.ts
@@ -16,20 +16,39 @@ declare global {
   }
 }
 
-// RIC and shim for browsers setTimeout() without it
-const requestIdleCallback =
-  window.requestIdleCallback ||
-  function requestIdleCallback(cb: CallableFunction) {
-    const start = Date.now();
-    return setTimeout(() => {
-      cb({
-        didTimeout: false,
-        timeRemaining() {
-          return Math.max(0, 50 - (Date.now() - start));
-        },
-      });
-    }, 1);
+function idleCall(cb: IdleRequestCallback, start: number) {
+  cb({
+    didTimeout: false,
+    timeRemaining() {
+      return Math.max(0, 50 - (Date.now() - start));
+    },
+  });
+}
+
+// RIC and shim for browsers setTimeout() without it idle
+let requestIdleCallback: (cb: IdleRequestCallback) => any;
+if (typeof window.requestIdleCallback !== 'undefined') {
+  requestIdleCallback = window.requestIdleCallback;
+} else if (typeof window.MessageChannel !== 'undefined') {
+  // The first recommendation is to use MessageChannel because
+  // it does not have the 4ms delay of setTimeout
+  const channel = new MessageChannel();
+  const port = channel.port2;
+  const tasks: IdleRequestCallback[] = [];
+  channel.port1.onmessage = ({ data }) => {
+    const task = tasks.shift();
+    if (!task) {
+      return;
+    }
+    idleCall(task, data.start);
   };
+  requestIdleCallback = function(cb: IdleRequestCallback) {
+    tasks.push(cb);
+    port.postMessage({ start: Date.now() });
+  };
+} else {
+  requestIdleCallback = (cb: IdleRequestCallback) => setTimeout(idleCall, 0, cb, Date.now());
+}
 
 declare global {
   interface Navigator {