lib: faster internal createBlob

PR-URL: nodejs#49730
Reviewed-By: Yagiz Nizipli <[email protected]>
Reviewed-By: Zeyu "Alex" Yang <[email protected]>
Reviewed-By: Matthew Aitken <[email protected]>
Reviewed-By: Benjamin Gruenbaum <[email protected]>
Reviewed-By: Rafael Gonzaga <[email protected]>
Reviewed-By: Stephen Belanger <[email protected]>

Author: H4ad

lib/internal/blob.js

@@ -6,6 +6,7 @@ const {
   MathMin,
   ObjectDefineProperties,
   ObjectDefineProperty,
+  ObjectSetPrototypeOf,
   PromiseReject,
   ReflectConstruct,
   RegExpPrototypeExec,
@@ -391,13 +392,23 @@ function ClonedBlob() {
 }
 ClonedBlob.prototype[kDeserialize] = () => {};
 
+function TransferrableBlob(handle, length, type = '') {
+  markTransferMode(this, true, false);
+  this[kHandle] = handle;
+  this[kType] = type;
+  this[kLength] = length;
+}
+
+ObjectSetPrototypeOf(TransferrableBlob.prototype, Blob.prototype);
+ObjectSetPrototypeOf(TransferrableBlob, Blob);
+
 function createBlob(handle, length, type = '') {
-  return ReflectConstruct(function() {
-    markTransferMode(this, true, false);
-    this[kHandle] = handle;
-    this[kType] = type;
-    this[kLength] = length;
-  }, [], Blob);
+  const transferredBlob = new TransferrableBlob(handle, length, type);
+
+  // Fix issues like: https://github.com/nodejs/node/pull/49730#discussion_r1331720053
+  transferredBlob.constructor = Blob;
+
+  return transferredBlob;
 }
 
 ObjectDefineProperty(Blob.prototype, SymbolToStringTag, {

test/parallel/test-blob-createobjecturl.js

@@ -24,6 +24,8 @@ const assert = require('assert');
   const id = URL.createObjectURL(blob);
   assert.strictEqual(typeof id, 'string');
   const otherBlob = resolveObjectURL(id);
+  assert.ok(otherBlob instanceof Blob);
+  assert.strictEqual(otherBlob.constructor, Blob);
   assert.strictEqual(otherBlob.size, 5);
   assert.strictEqual(
     Buffer.from(await otherBlob.arrayBuffer()).toString(),

test/parallel/test-blob.js

@@ -473,3 +473,10 @@ assert.throws(() => new Blob({}), {
 
   await new Blob(chunks).arrayBuffer();
 })().then(common.mustCall());
+
+{
+  const blob = new Blob(['hello']);
+
+  assert.ok(blob.slice(0, 1).constructor === Blob);
+  assert.ok(blob.slice(0, 1) instanceof Blob);
+}