fix(page): fallback to default in exposeFunction when using imported module (#6365)

docs/api.md

@@ -1875,7 +1875,7 @@ await page.evaluateOnNewDocument(preloadFile);
 #### page.exposeFunction(name, puppeteerFunction)
 
 - `name` <[string]> Name of the function on the window object
-- `puppeteerFunction` <[function]> Callback function which will be called in Puppeteer's context.
+- `puppeteerFunction` <[function]> Callback function which will be called in Puppeteer's context. Can also be a module with a default export.
 - returns: <[Promise]>
 
 The method adds a function called `name` on the page's `window` object.

src/common/Page.ts

@@ -1364,13 +1364,25 @@ export class Page extends EventEmitter {
    */
   async exposeFunction(
     name: string,
-    puppeteerFunction: Function
+    puppeteerFunction: Function | { default: Function }
   ): Promise<void> {
     if (this._pageBindings.has(name))
       throw new Error(
         `Failed to add page binding with name ${name}: window['${name}'] already exists!`
       );
-    this._pageBindings.set(name, puppeteerFunction);
+
+    let exposedFunction: Function;
+    if (typeof puppeteerFunction === 'function') {
+      exposedFunction = puppeteerFunction;
+    } else if (typeof puppeteerFunction.default === 'function') {
+      exposedFunction = puppeteerFunction.default;
+    } else {
+      throw new Error(
+        `Failed to add page binding with name ${name}: ${puppeteerFunction} is not a function or a module with a default export.`
+      );
+    }
+
+    this._pageBindings.set(name, exposedFunction);
 
     const expression = helper.pageBindingInitString('exposedFun', name);
     await this._client.send('Runtime.addBinding', { name: name });

test/page.spec.ts

@@ -1029,6 +1029,20 @@ describe('Page', function () {
       );
       expect(result.x).toBe(7);
     });
+    it('should fallback to default export when passed a module object', async () => {
+      const { page, server } = getTestState();
+      const moduleObject = {
+        default: function (a, b) {
+          return a * b;
+        },
+      };
+      await page.goto(server.EMPTY_PAGE);
+      await page.exposeFunction('compute', moduleObject);
+      const result = await page.evaluate(async function () {
+        return await globalThis.compute(9, 4);
+      });
+      expect(result).toBe(36);
+    });
   });
 
   describeFailsFirefox('Page.Events.PageError', function () {