fix: handle null options in addEventHandler #9371 (#9372)

ThibautMarechal · web-flow · commit 40841ff005cf · 2026-01-04T12:23:31.000+01:00
diff --git a/packages/vitest/src/integrations/env/jsdom.ts b/packages/vitest/src/integrations/env/jsdom.ts
@@ -328,7 +328,7 @@ function patchAddEventListener(window: DOMWindow) {
     callback: EventListenerOrEventListenerObject | null,
     options?: AddEventListenerOptions | boolean,
   ) {
-    if (typeof options === 'object' && options.signal != null) {
+    if (typeof options === 'object' && options?.signal != null) {
       const { signal, ...otherOptions } = options
       // - this happens because AbortSignal is provided by Node.js,
       // but jsdom APIs require jsdom's AbortSignal, while Node APIs
diff --git a/test/core/test/environments/jsdom.spec.ts b/test/core/test/environments/jsdom.spec.ts
@@ -226,6 +226,20 @@ test('can pass down the same abort signal many times without a warning', ({ onTe
   }))
 })
 
+test('DOM APIs addEventListener allow null as third parameter', () => {
+  const element = document.createElement('div')
+  document.body.append(element)
+  const spy = vi.fn()
+
+  // eslint-disable-next-line ts/ban-ts-comment
+  // @ts-expect-error
+  element.addEventListener('click', spy, null)
+
+  element.click()
+
+  expect(spy).toHaveBeenCalledTimes(1)
+})
+
 test('atob and btoa are available', () => {
   expect(atob('aGVsbG8gd29ybGQ=')).toBe('hello world')
   expect(btoa('hello world')).toBe('aGVsbG8gd29ybGQ=')
