LibJS: Expose TypedArray.prototype.buffer

Userland/Libraries/LibJS/Tests/builtins/TypedArray/TypedArray.prototype.buffer.js

@@ -0,0 +1,31 @@
+// Update when more typed arrays get added
+const TYPED_ARRAYS = [
+    Uint8Array,
+    Uint16Array,
+    Uint32Array,
+    Int8Array,
+    Int16Array,
+    Int32Array,
+    Float32Array,
+    Float64Array,
+];
+
+test("basic functionality", () => {
+    TYPED_ARRAYS.forEach(T => {
+        const typedArray = new T([1, 2, 3]);
+        expect(Object.hasOwn(typedArray, "byteOffset")).toBeFalse();
+
+        const buffer = typedArray.buffer;
+        expect(buffer).toBeInstanceOf(ArrayBuffer);
+        expect(buffer.byteLength).toBe(typedArray.byteLength);
+        expect(buffer.byteLength).toBe(typedArray.length * typedArray.BYTES_PER_ELEMENT);
+
+        const arrayFromBuffer = new T(buffer);
+        expect(arrayFromBuffer.length).toBe(typedArray.length);
+        expect(arrayFromBuffer.byteLength).toBe(typedArray.byteLength);
+        expect(arrayFromBuffer.byteOffset).toBe(typedArray.byteOffset);
+        expect(arrayFromBuffer[0]).toBe(typedArray[0]);
+        expect(arrayFromBuffer[1]).toBe(typedArray[1]);
+        expect(arrayFromBuffer[2]).toBe(typedArray[2]);
+    });
+});