Merge pull request #38 from pendo-io/ai-angular-zone-fix

Use alternative angular zone detection in getUntaintedPrototype

Author: pendo-ops

packages/utils/src/index.ts

@@ -28,14 +28,48 @@ const testableMethods = {
 
 const untaintedBasePrototype: Partial<BasePrototypeCache> = {};
 
+type WindowWithZone = typeof globalThis & {
+  Zone?: {
+    __symbol__?: (key: string) => string;
+  };
+};
+
+type WindowWithUnpatchedSymbols = typeof globalThis &
+  Record<string, TypeofPrototypeOwner>;
+
+/*
+Angular zone patches many things and can pass the untainted checks below, causing performance issues
+Angular zone, puts the unpatched originals on the window, and the names for hose on the zone object.
+So, we get the unpatched versions from the window object if they exist.
+You can rename Zone, but this is a good enough proxy to avoid going to an iframe to get the untainted versions.
+see: https://github.com/angular/angular/issues/26948
+*/
+function angularZoneUnpatchedAlternative(key: keyof BasePrototypeCache) {
+  const angularUnpatchedVersionSymbol = (
+    globalThis as WindowWithZone
+  )?.Zone?.__symbol__?.(key);
+  if (
+    angularUnpatchedVersionSymbol &&
+    (globalThis as WindowWithUnpatchedSymbols)[angularUnpatchedVersionSymbol]
+  ) {
+    return (globalThis as WindowWithUnpatchedSymbols)[
+      angularUnpatchedVersionSymbol
+    ];
+  } else {
+    return undefined;
+  }
+}
+
 export function getUntaintedPrototype<T extends keyof BasePrototypeCache>(
   key: T,
 ): BasePrototypeCache[T] {
   if (untaintedBasePrototype[key])
     return untaintedBasePrototype[key] as BasePrototypeCache[T];
 
-  const defaultObj = globalThis[key] as TypeofPrototypeOwner;
-  const defaultPrototype = defaultObj.prototype as BasePrototypeCache[T];
+  const candidate =
+    angularZoneUnpatchedAlternative(key) ||
+    (globalThis[key] as TypeofPrototypeOwner);
+  const defaultPrototype = candidate.prototype as BasePrototypeCache[T];
 
   // use list of testable accessors to check if the prototype is tainted
   const accessorNames =
@@ -64,15 +98,15 @@ export function getUntaintedPrototype<T extends keyof BasePrototypeCache>(
   );
 
   if (isUntaintedAccessors && isUntaintedMethods) {
-    untaintedBasePrototype[key] = defaultObj.prototype as BasePrototypeCache[T];
-    return defaultObj.prototype as BasePrototypeCache[T];
+    untaintedBasePrototype[key] = candidate.prototype as BasePrototypeCache[T];
+    return candidate.prototype as BasePrototypeCache[T];
   }
 
   try {
     const iframeEl = document.createElement('iframe');
     document.body.appendChild(iframeEl);
     const win = iframeEl.contentWindow;
-    if (!win) return defaultObj.prototype as BasePrototypeCache[T];
+    if (!win) return candidate.prototype as BasePrototypeCache[T];
 
     // eslint-disable-next-line @typescript-eslint/no-unsafe-assignment, @typescript-eslint/no-unsafe-member-access, @typescript-eslint/no-explicit-any
     const untaintedObject = (win as any)[key]