fix(addInitScript): require non-undefined arg to trigger commonjs module (#32282)

docs/src/api/class-browsercontext.md

@@ -439,9 +439,9 @@ const mockPath = { path: path.resolve(__dirname, '../mocks/mockRandom.js') };
 // Passing 42 as an argument to the default export function.
 await context.addInitScript({ path: mockPath }, 42);
 
-// Make sure to pass undefined even if you do not need to pass an argument.
+// Make sure to pass something even if you do not need to pass an argument.
 // This instructs Playwright to treat the file as a commonjs module.
-await context.addInitScript({ path: mockPath }, undefined);
+await context.addInitScript({ path: mockPath }, '');
 ```
 
 ### param: BrowserContext.addInitScript.script

docs/src/api/class-page.md

@@ -643,9 +643,9 @@ const mockPath = { path: path.resolve(__dirname, '../mocks/mockRandom.js') };
 // Passing 42 as an argument to the default export function.
 await page.addInitScript({ path: mockPath }, 42);
 
-// Make sure to pass undefined even if you do not need to pass an argument.
+// Make sure to pass something even if you do not need to pass an argument.
 // This instructs Playwright to treat the file as a commonjs module.
-await page.addInitScript({ path: mockPath }, undefined);
+await page.addInitScript({ path: mockPath }, '');
 ```
 
 ### param: Page.addInitScript.script

packages/playwright-core/src/client/browserContext.ts

@@ -308,7 +308,7 @@ export class BrowserContext extends ChannelOwner<channels.BrowserContextChannel>
   }
 
   async addInitScript(script: Function | string | { path?: string, content?: string }, arg?: any): Promise<void> {
-    const source = await evaluationScript(script, arg, arguments.length > 1);
+    const source = await evaluationScript(script, arg);
     await this._channel.addInitScript({ source });
   }
 

packages/playwright-core/src/client/clientHelper.ts

@@ -28,7 +28,7 @@ export function envObjectToArray(env: types.Env): { name: string, value: string
   return result;
 }
 
-export async function evaluationScript(fun: Function | string | { path?: string, content?: string }, arg: any, hasArg: boolean, addSourceUrl: boolean = true): Promise<string> {
+export async function evaluationScript(fun: Function | string | { path?: string, content?: string }, arg: any, addSourceUrl: boolean = true): Promise<string> {
   if (typeof fun === 'function') {
     const source = fun.toString();
     const argString = Object.is(arg, undefined) ? 'undefined' : JSON.stringify(arg);
@@ -46,7 +46,7 @@ export async function evaluationScript(fun: Function | string | { path?: string,
   }
   if (fun.path !== undefined) {
     let source = await fs.promises.readFile(fun.path, 'utf8');
-    if (hasArg) {
+    if (arg !== undefined) {
       // Assume a CJS module that has a function default export.
       source = `(() => {
         var exports = {}; var module = { exports };

packages/playwright-core/src/client/page.ts

@@ -492,7 +492,7 @@ export class Page extends ChannelOwner<channels.PageChannel> implements api.Page
   }
 
   async addInitScript(script: Function | string | { path?: string, content?: string }, arg?: any) {
-    const source = await evaluationScript(script, arg, arguments.length > 1);
+    const source = await evaluationScript(script, arg);
     await this._channel.addInitScript({ source });
   }
 

packages/playwright-core/src/client/selectors.ts

@@ -26,7 +26,7 @@ export class Selectors implements api.Selectors {
   private _registrations: channels.SelectorsRegisterParams[] = [];
 
   async register(name: string, script: string | (() => SelectorEngine) | { path?: string, content?: string }, options: { contentScript?: boolean } = {}): Promise<void> {
-    const source = await evaluationScript(script, undefined, false, false);
+    const source = await evaluationScript(script, undefined, false);
     const params = { ...options, name, source };
     for (const channel of this._channels)
       await channel._channel.register(params);

packages/playwright-core/types/types.d.ts

@@ -312,9 +312,9 @@ export interface Page {
    * // Passing 42 as an argument to the default export function.
    * await page.addInitScript({ path: mockPath }, 42);
    *
-   * // Make sure to pass undefined even if you do not need to pass an argument.
+   * // Make sure to pass something even if you do not need to pass an argument.
    * // This instructs Playwright to treat the file as a commonjs module.
-   * await page.addInitScript({ path: mockPath }, undefined);
+   * await page.addInitScript({ path: mockPath }, '');
    * ```
    *
    * @param script Script to be evaluated in the page.
@@ -7723,9 +7723,9 @@ export interface BrowserContext {
    * // Passing 42 as an argument to the default export function.
    * await context.addInitScript({ path: mockPath }, 42);
    *
-   * // Make sure to pass undefined even if you do not need to pass an argument.
+   * // Make sure to pass something even if you do not need to pass an argument.
    * // This instructs Playwright to treat the file as a commonjs module.
-   * await context.addInitScript({ path: mockPath }, undefined);
+   * await context.addInitScript({ path: mockPath }, '');
    * ```
    *
    * @param script Script to be evaluated in all pages in the browser context.

tests/page/page-add-init-script.spec.ts

@@ -37,12 +37,6 @@ it('should assume CJS module with a path and arg', async ({ page, server, asset
   expect(await page.evaluate(() => window['injected'])).toBe(17);
 });
 
-it('should assume CJS module with a path and undefined arg', async ({ page, server, asset }) => {
-  await page.addInitScript({ path: asset('injectedmodule.js') }, undefined);
-  await page.goto(server.EMPTY_PAGE);
-  expect(await page.evaluate(() => window['injected'])).toBe(42);
-});
-
 it('should work with content @smoke', async ({ page, server }) => {
   await page.addInitScript({ content: 'window["injected"] = 123' });
   await page.goto(server.PREFIX + '/tamperable.html');