Fixes potential ReferenceError in Polyfills (#76)

configcat · Jan 3, 2023 · d627118 · d627118
1 parent 7e1c5ba
commit d627118
Show file tree

Hide file tree

Showing 2 changed files with 25 additions and 4 deletions.
diff --git a/src/Polyfills.ts b/src/Polyfills.ts
@@ -1,3 +1,24 @@
+const getGlobalObject = (() => {
+    let value: typeof globalThis | undefined;
+
+    return () => {
+        if (!value) {
+            value =
+                typeof globalThis === "object" && globalThis ? globalThis :
+                typeof self === "object" && self ? self :
+                typeof window === "object" && window ? window :
+                typeof global === "object" && global ? global :
+                typeof Function === "function" ? (Function('return this')()) :
+                null;
+
+            if (!value) {
+                throw new Error("Global object could not be determined.");
+            }
+        }
+        return value;
+    };
+})();
+
 export function setupPolyfills() {
     // Object.values
     if (typeof Object.values === "undefined") {
@@ -18,7 +39,7 @@ export function setupPolyfills() {
     if (typeof WeakRef === "undefined") {
         // There's no way to correctly polyfill WeakRef (https://stackoverflow.com/a/69971312/8656352),
         // so we just polyfill its API (which means falling back on strong references in this case).
-        WeakRef = getWeakRefFallback();
+        getGlobalObject().WeakRef = getWeakRefStub();
     }
 }
 
@@ -59,7 +80,7 @@ export function ObjectFromEntriesPolyfill<T>(entries: Iterable<readonly [Propert
     return result;
 }
 
-export function getWeakRefFallback<T extends object>(): WeakRefConstructor {
+export function getWeakRefStub<T extends object>(): WeakRefConstructor {
     type WeakRefImpl = WeakRef<T> & { target: T };
 
     const WeakRef = function (this: WeakRefImpl, target: T) {

diff --git a/test/PolyfillTests.ts b/test/PolyfillTests.ts
@@ -1,6 +1,6 @@
 import { assert, expect } from "chai";
 import "mocha";
-import { getWeakRefFallback, ObjectEntriesPolyfill, ObjectFromEntriesPolyfill, ObjectValuesPolyfill } from "../src/Polyfills";
+import { getWeakRefStub, ObjectEntriesPolyfill, ObjectFromEntriesPolyfill, ObjectValuesPolyfill } from "../src/Polyfills";
 
 describe("Polyfills", () => {
     it("Object.values polyfill should work", () => {
@@ -36,7 +36,7 @@ describe("Polyfills", () => {
     });
 
     it("WeakRef API polyfill should work", () => {
-        const weakRefCtor = getWeakRefFallback();
+        const weakRefCtor = getWeakRefStub();
 
         let obj: {} | null = {};
         const objWeakRef = new weakRefCtor(obj);