get name if not provided in `FormData.append` (#4434)

* get file name from blob if not provided

* add test

* another test

* format

1 files changed, 30 insertions, 0 deletions

diff --git a/test/js/web/html/FormData.test.ts b/test/js/web/html/FormData.test.ts
index c742bd33e..5e4861bc8 100644
--- a/test/js/web/html/FormData.test.ts
+++ b/test/js/web/html/FormData.test.ts
@@ -36,6 +36,36 @@ describe("FormData", () => {
     expect(formData.getAll("foo")[0]).toBe("bar");
   });
 
+  it("should get filename from file", async () => {
+    const blob = new Blob(["bar"]);
+    const formData = new FormData();
+    formData.append("foo", blob);
+    // @ts-expect-error
+    expect(formData.get("foo").name).toBeUndefined();
+    formData.append("foo2", new File([blob], "foo.txt"));
+    // @ts-expect-error
+    expect(formData.get("foo2").name).toBe("foo.txt");
+  });
+
+  it("should use the correct filenames", async () => {
+    const blob = new Blob(["bar"]) as any;
+    const form = new FormData();
+    form.append("foo", blob);
+    expect(blob.name).toBeUndefined();
+
+    let b1 = form.get("foo") as any;
+    expect(blob.name).toBeUndefined();
+    expect(b1.name).toBeUndefined();
+
+    form.set("foo", b1, "foo.txt");
+    expect(blob.name).toBeUndefined();
+    expect(b1.name).toBeUndefined();
+
+    b1 = form.get("foo") as Blob;
+    expect(blob.name).toBeUndefined();
+    expect(b1.name).toBe("foo.txt");
+  });
+
   const multipartFormDataFixturesRawBody = [
     {
       name: "simple",