[primitives] don't override Blob global (#359)

.changeset/afraid-garlics-fail.md

@@ -0,0 +1,5 @@
+---
+'@edge-runtime/primitives': patch
+---
+
+Don't remove Blob from global scope, and use global Blob if available

packages/integration-tests/tests/blob.test.ts

@@ -0,0 +1,8 @@
+const test18 = process.version.startsWith('v18.') ? test : test.skip
+
+test18('Blob is available globally after importing the ponyfill', () => {
+  const blob = Blob
+  expect(blob).toBeDefined()
+  require('@edge-runtime/ponyfill')
+  expect(Blob).toBe(blob)
+})

packages/primitives/scripts/build.ts

@@ -119,26 +119,6 @@ async function bundlePackage() {
           )
         },
       },
-      /**
-       * Modern Node.js versions include Blob globally which makes the Blob
-       * polyfill fail as if it was running on the browser so we attempt to
-       * remove if from `global` always.
-       */
-      {
-        name: 'hide-builtin-blob',
-        setup: (build) => {
-          build.onLoad({ filter: /blob-polyfill/ }, async (args) => {
-            return {
-              contents: Buffer.concat([
-                Buffer.from(
-                  `(() => { try { global.Blob = undefined; } catch {} })(); `
-                ),
-                await fs.promises.readFile(args.path),
-              ]),
-            }
-          })
-        },
-      },
     ],
   })
 

packages/primitives/src/primitives/load.js

@@ -1,4 +1,5 @@
 // @ts-check
+/// <reference path="../injectSourceCode.d.ts" />
 
 import Module from 'module'
 import nodeCrypto from 'crypto'
@@ -152,12 +153,32 @@ export function load(scopedContext = {}) {
   })
 
   /** @type {import('../../type-definitions/blob')} */
-  const blobImpl = requireWithFakeGlobalScope({
-    context,
-    id: 'blob.js',
-    sourceCode: injectSourceCode('./blob.js'),
-    scopedContext: { ...streamsImpl, ...scopedContext },
-  })
+  const blobImpl = (() => {
+    if (typeof scopedContext.Blob === 'function') {
+      return { Blob: scopedContext.Blob }
+    }
+
+    if (typeof Blob === 'function') {
+      return { Blob }
+    }
+
+    /** @type {any} */
+    const global = {
+      ...streamsImpl,
+      ...scopedContext,
+    }
+
+    const globalGlobal = { ...global, Blob: undefined }
+    Object.setPrototypeOf(globalGlobal, globalThis)
+
+    global.global = globalGlobal
+    return requireWithFakeGlobalScope({
+      context,
+      id: 'blob.js',
+      sourceCode: injectSourceCode('./blob.js'),
+      scopedContext: global,
+    })
+  })()
   assign(context, {
     Blob: blobImpl.Blob,
   })