fix(jsdom): support Blob on jsdom 30.1

examples/lit/package.json

@@ -18,7 +18,7 @@
   },
   "devDependencies": {
     "@vitest/browser-playwright": "latest",
-    "jsdom": "^29.1.1",
+    "jsdom": "^30.1.1",
     "playwright": "^1.62.1",
     "vite": "latest",
     "vitest": "latest"

examples/projects/package.json

@@ -16,7 +16,7 @@
     "@vitejs/plugin-react": "^5.2.0",
     "@vitest/ui": "latest",
     "fastify": "^5.12.1",
-    "jsdom": "^29.1.1",
+    "jsdom": "^30.1.1",
     "react": "^19.2.8",
     "supertest": "^7.2.2",
     "tsx": "^4.23.13",

packages/vitest/package.json

@@ -187,7 +187,7 @@
     "@jridgewell/trace-mapping": "catalog:",
     "@opentelemetry/api": "^1.9.1",
     "@sinonjs/fake-timers": "15.4.0",
-    "@types/jsdom": "^28.0.3",
+    "@types/jsdom": "^30.0.0",
     "@types/node": "^24.13.3",
     "@types/picomatch": "^4.0.3",
     "@types/prompts": "^2.4.9",
@@ -204,7 +204,7 @@
     "cac": "catalog:",
     "flatted": "catalog:",
     "happy-dom": "^20.12.0",
-    "jsdom": "^29.1.1",
+    "jsdom": "^30.1.1",
     "local-pkg": "^1.2.1",
     "mime": "^4.1.0",
     "pathe": "catalog:",

packages/vitest/src/integrations/env/jsdom.ts

@@ -1,6 +1,7 @@
 import type { ConstructorOptions, DOMWindow, VirtualConsole as IVirtualConsole } from 'jsdom'
 import type { Environment } from '../../types/environment'
 import type { JSDOMOptions } from '../../types/jsdom-options'
+import { createRequire } from 'node:module'
 import { URL as NodeURL } from 'node:url'
 import { populateGlobal } from './utils'
 
@@ -292,12 +293,31 @@ interface CompatUtils {
   makeCompatFormData: (formData: FormData) => FormData
 }
 
+// jsdom keeps Blob bytes on an internal "impl" object and exposes no synchronous
+// public way to read them, so this reaches into its generated bindings
+function createBlobImplGetter(window: DOMWindow): (blob: Blob) => any {
+  const _require = createRequire(import.meta.url)
+  // jsdom 28.1 moved the generated bindings; jsdom has no "exports" map, so both subpaths resolve
+  for (const id of [
+    'jsdom/lib/generated/idl/utils.js',
+    'jsdom/lib/jsdom/living/generated/utils.js',
+  ]) {
+    try {
+      const { implForWrapper } = _require(id)
+      if (typeof implForWrapper === 'function') {
+        return implForWrapper
+      }
+    } catch {}
+  }
+  // jsdom < 30.1 also stores the impl under an own Symbol("impl")
+  const implSymbol = Object.getOwnPropertySymbols(new window.Blob())[0]
+  return (blob) => (blob as any)[implSymbol]
+}
+
+let getBlobImpl: (blob: Blob) => any
+
 function createCompatUtils(window: DOMWindow): CompatUtils {
-  // this returns a hidden Symbol(impl)
-  // this is cursed, and jsdom should just implement fetch API itself
-  const implSymbol = Object.getOwnPropertySymbols(
-    Object.getOwnPropertyDescriptors(new window.Blob()),
-  )[0]
+  getBlobImpl ??= createBlobImplGetter(window)
   const utils = {
     window,
     makeCompatFormData(formData: FormData) {
@@ -312,7 +332,12 @@ function createCompatUtils(window: DOMWindow): CompatUtils {
       return nodeFormData
     },
     makeCompatBlob(blob: Blob) {
-      const impl = (blob as any)[implSymbol]
+      const impl = getBlobImpl(blob)
+      if (!impl) {
+        throw new TypeError(
+          'Vitest cannot read the bytes of a jsdom Blob. This is a Vitest bug, please report it with your jsdom version.',
+        )
+      }
       // jsdom 28 renamed `_buffer` to `_bytes`
       return new NodeBlob_([impl._bytes ?? impl._buffer], { type: blob.type })
     },