Improve the polifill for setImmediate for max performance

src/libs/set-immediate-polyfill.ts

@@ -0,0 +1,42 @@
+const originalSetImmediate = (globalThis as any).setImmediate
+let setImmediateChannel: MessageChannel | null = null
+const setImmediateQueue: (() => void)[] = []
+
+function immediatePolyfill(callback: (...args: any[]) => void, ...args: any[]) {
+  if (typeof originalSetImmediate === 'function') {
+    return originalSetImmediate(callback, ...args)
+  }
+
+  if (typeof MessageChannel !== 'undefined') {
+    if (!setImmediateChannel) {
+      setImmediateChannel = new MessageChannel()
+      setImmediateChannel.port1.addEventListener('message', () => {
+        const fn = setImmediateQueue.shift()
+        if (fn) {
+          try {
+            fn()
+          } catch {}
+        }
+      })
+      setImmediateChannel.port1.start()
+    }
+    setImmediateQueue.push(() => callback(...args))
+    setImmediateChannel.port2.postMessage(0)
+    return 0
+  }
+
+  return setTimeout(() => callback(...args), 0)
+}
+
+export function installSetImmediatePolyfill() {
+  if (typeof (globalThis as any).setImmediate === 'function') {
+    return
+  }
+  ;(globalThis as any).setImmediate = immediatePolyfill
+}
+
+export function uninstallSetImmediatePolyfill() {
+  if ((globalThis as any).setImmediate === immediatePolyfill) {
+    delete (globalThis as any).setImmediate
+  }
+}

src/libs/utils.ts

@@ -1,6 +1,9 @@
 import { ResolvableFile } from '../classes/resolvable-file.ts'
+import { uninstallSetImmediatePolyfill } from './set-immediate-polyfill.ts'
 import { vendors } from './vendors.ts'
 
+export { installSetImmediatePolyfill, uninstallSetImmediatePolyfill } from './set-immediate-polyfill.ts'
+
 const { path } = vendors
 
 export const textEncoder = new TextEncoder()
@@ -238,24 +241,3 @@ export function isZip(uint8Array: Uint8Array) {
     (uint8Array[3] === 0x04 || uint8Array[3] === 0x06 || uint8Array[3] === 0x08)
   )
 }
-
-const originalSetImmediate = globalThis.setImmediate
-function setImmediate(callback: any) {
-  // eslint-disable-next-line @typescript-eslint/no-implied-eval
-  return originalSetImmediate ? originalSetImmediate(callback) : setTimeout(callback, 0)
-}
-
-export function installSetImmediatePolyfill() {
-  if (typeof globalThis.setImmediate === 'function') {
-    return
-  }
-  // @ts-expect-error polyfill
-  globalThis.setImmediate = setImmediate
-}
-
-export function uninstallSetImmediatePolyfill() {
-  if (globalThis.setImmediate === setImmediate) {
-    // @ts-expect-error remove polyfill
-    delete globalThis.setImmediate
-  }
-}