LibWeb: Port IDL implementations Blob and File to new String

Userland/Libraries/LibWeb/Fetch/Body.cpp

@@ -108,7 +108,7 @@ WebIDL::ExceptionOr<JS::Value> package_data(JS::Realm& realm, ByteBuffer bytes,
     case PackageDataType::Blob: {
         // Return a Blob whose contents are bytes and type attribute is mimeType.
         // NOTE: If extracting the mime type returns failure, other browsers set it to an empty string - not sure if that's spec'd.
-        auto mime_type_string = mime_type.has_value() ? mime_type->serialized() : DeprecatedString::empty();
+        auto mime_type_string = mime_type.has_value() ? TRY_OR_THROW_OOM(vm, String::from_deprecated_string(mime_type->serialized())) : String {};
         return TRY(FileAPI::Blob::create(realm, move(bytes), move(mime_type_string)));
     }
     case PackageDataType::FormData:

Userland/Libraries/LibWeb/Fetch/BodyInit.cpp

@@ -75,7 +75,7 @@ WebIDL::ExceptionOr<Infrastructure::BodyWithType> extract_body(JS::Realm& realm,
             length = blob->size();
             // If object’s type attribute is not the empty byte sequence, set type to its value.
             if (!blob->type().is_empty())
-                type = blob->type().to_byte_buffer();
+                type = TRY_OR_THROW_OOM(vm, ByteBuffer::copy(blob->type().bytes()));
             return {};
         },
         [&](ReadonlyBytes bytes) -> WebIDL::ExceptionOr<void> {

Userland/Libraries/LibWeb/FileAPI/Blob.cpp

@@ -1,27 +1,28 @@
 /*
- * Copyright (c) 2022, Kenneth Myhra <kennethmyhra@serenityos.org>
+ * Copyright (c) 2022-2023, Kenneth Myhra <kennethmyhra@serenityos.org>
  *
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
 #include <AK/GenericLexer.h>
-#include <AK/StdLibExtras.h>
 #include <LibJS/Runtime/ArrayBuffer.h>
 #include <LibJS/Runtime/Completion.h>
 #include <LibWeb/Bindings/BlobPrototype.h>
+#include <LibWeb/Bindings/ExceptionOrUtils.h>
 #include <LibWeb/Bindings/Intrinsics.h>
 #include <LibWeb/FileAPI/Blob.h>
+#include <LibWeb/Infra/Strings.h>
 #include <LibWeb/WebIDL/AbstractOperations.h>
 
 namespace Web::FileAPI {
 
-WebIDL::ExceptionOr<JS::NonnullGCPtr<Blob>> Blob::create(JS::Realm& realm, ByteBuffer byte_buffer, DeprecatedString type)
+WebIDL::ExceptionOr<JS::NonnullGCPtr<Blob>> Blob::create(JS::Realm& realm, ByteBuffer byte_buffer, String type)
 {
     return MUST_OR_THROW_OOM(realm.heap().allocate<Blob>(realm, realm, move(byte_buffer), move(type)));
 }
 
 // https://w3c.github.io/FileAPI/#convert-line-endings-to-native
-ErrorOr<DeprecatedString> convert_line_endings_to_native(DeprecatedString const& string)
+ErrorOr<String> convert_line_endings_to_native(StringView string)
 {
     // 1. Let native line ending be be the code point U+000A LF.
     auto native_line_ending = "\n"sv;
@@ -33,7 +34,7 @@ ErrorOr<DeprecatedString> convert_line_endings_to_native(DeprecatedString const&
     StringBuilder result;
 
     // 4. Let position be a position variable for s, initially pointing at the start of s.
-    auto lexer = GenericLexer { string.view() };
+    auto lexer = GenericLexer { string };
 
     // 5. Let token be the result of collecting a sequence of code points that are not equal to U+000A LF or U+000D CR from s given position.
     // 6. Append token to result.
@@ -64,7 +65,7 @@ ErrorOr<DeprecatedString> convert_line_endings_to_native(DeprecatedString const&
         TRY(result.try_append(lexer.consume_until(is_any_of("\n\r"sv))));
     }
     // 5. Return result.
-    return result.to_deprecated_string();
+    return result.to_string();
 }
 
 // https://w3c.github.io/FileAPI/#process-blob-parts
@@ -77,7 +78,7 @@ ErrorOr<ByteBuffer> process_blob_parts(Vector<BlobPart> const& blob_parts, Optio
     for (auto const& blob_part : blob_parts) {
         TRY(blob_part.visit(
             // 1. If element is a USVString, run the following sub-steps:
-            [&](DeprecatedString const& string) -> ErrorOr<void> {
+            [&](String const& string) -> ErrorOr<void> {
                 // 1. Let s be element.
                 auto s = string;
 
@@ -85,9 +86,9 @@ ErrorOr<ByteBuffer> process_blob_parts(Vector<BlobPart> const& blob_parts, Optio
                 if (options.has_value() && options->endings == Bindings::EndingType::Native)
                     s = TRY(convert_line_endings_to_native(s));
 
-                // NOTE: The AK::DeprecatedString is always UTF-8.
+                // NOTE: The AK::String is always UTF-8.
                 // 3. Append the result of UTF-8 encoding s to bytes.
-                return bytes.try_append(s.to_byte_buffer());
+                return bytes.try_append(s.bytes());
             },
             // 2. If element is a BufferSource, get a copy of the bytes held by the buffer source, and append those bytes to bytes.
             [&](JS::Handle<JS::Object> const& buffer_source) -> ErrorOr<void> {
@@ -117,7 +118,7 @@ Blob::Blob(JS::Realm& realm)
 {
 }
 
-Blob::Blob(JS::Realm& realm, ByteBuffer byte_buffer, DeprecatedString type)
+Blob::Blob(JS::Realm& realm, ByteBuffer byte_buffer, String type)
     : PlatformObject(realm)
     , m_byte_buffer(move(byte_buffer))
     , m_type(move(type))
@@ -143,6 +144,8 @@ JS::ThrowCompletionOr<void> Blob::initialize(JS::Realm& realm)
 // https://w3c.github.io/FileAPI/#ref-for-dom-blob-blob
 WebIDL::ExceptionOr<JS::NonnullGCPtr<Blob>> Blob::create(JS::Realm& realm, Optional<Vector<BlobPart>> const& blob_parts, Optional<BlobPropertyBag> const& options)
 {
+    auto& vm = realm.vm();
+
     // 1. If invoked with zero parameters, return a new Blob object consisting of 0 bytes, with size set to 0, and with type set to the empty string.
     if (!blob_parts.has_value() && !options.has_value())
         return MUST_OR_THROW_OOM(realm.heap().allocate<Blob>(realm, realm));
@@ -153,7 +156,7 @@ WebIDL::ExceptionOr<JS::NonnullGCPtr<Blob>> Blob::create(JS::Realm& realm, Optio
         byte_buffer = TRY_OR_THROW_OOM(realm.vm(), process_blob_parts(blob_parts.value(), options));
     }
 
-    auto type = DeprecatedString::empty();
+    auto type = String {};
     // 3. If the type member of the options argument is not the empty string, run the following sub-steps:
     if (options.has_value() && !options->type.is_empty()) {
         // 1. If the type member is provided and is not the empty string, let t be set to the type dictionary member.
@@ -166,7 +169,7 @@ WebIDL::ExceptionOr<JS::NonnullGCPtr<Blob>> Blob::create(JS::Realm& realm, Optio
 
         // 2. Convert every character in t to ASCII lowercase.
         if (!type.is_empty())
-            type = options->type.to_lowercase();
+            type = TRY_OR_THROW_OOM(vm, Infra::to_ascii_lower_case(type));
     }
 
     // 4. Return a Blob object referring to bytes as its associated byte sequence, with its size set to the length of bytes, and its type set to the value of t from the substeps above.
@@ -179,8 +182,10 @@ WebIDL::ExceptionOr<JS::NonnullGCPtr<Blob>> Blob::construct_impl(JS::Realm& real
 }
 
 // https://w3c.github.io/FileAPI/#dfn-slice
-WebIDL::ExceptionOr<JS::NonnullGCPtr<Blob>> Blob::slice(Optional<i64> start, Optional<i64> end, Optional<DeprecatedString> const& content_type)
+WebIDL::ExceptionOr<JS::NonnullGCPtr<Blob>> Blob::slice(Optional<i64> start, Optional<i64> end, Optional<String> const& content_type)
 {
+    auto& vm = realm().vm();
+
     // 1. The optional start parameter is a value for the start point of a slice() call, and must be treated as a byte-order position, with the zeroth position representing the first byte.
     //    User agents must process slice() with start normalized according to the following:
     i64 relative_start;
@@ -218,17 +223,17 @@ WebIDL::ExceptionOr<JS::NonnullGCPtr<Blob>> Blob::slice(Optional<i64> start, Opt
 
     // 3. The optional contentType parameter is used to set the ASCII-encoded string in lower case representing the media type of the Blob.
     //    User agents must process the slice() with contentType normalized according to the following:
-    DeprecatedString relative_content_type;
+    String relative_content_type;
     if (!content_type.has_value()) {
         // a. If the contentType parameter is not provided, let relativeContentType be set to the empty string.
-        relative_content_type = "";
+        relative_content_type = String {};
     } else {
         // b. Else let relativeContentType be set to contentType and run the substeps below:
 
         // FIXME: 1. If relativeContentType contains any characters outside the range of U+0020 to U+007E, then set relativeContentType to the empty string and return from these substeps.
 
         // 2. Convert every character in relativeContentType to ASCII lowercase.
-        relative_content_type = content_type->to_lowercase();
+        relative_content_type = TRY_OR_THROW_OOM(vm, Infra::to_ascii_lower_case(content_type.value()));
     }
 
     // 4. Let span be max((relativeEnd - relativeStart), 0).
@@ -238,20 +243,23 @@ WebIDL::ExceptionOr<JS::NonnullGCPtr<Blob>> Blob::slice(Optional<i64> start, Opt
     // a. S refers to span consecutive bytes from this, beginning with the byte at byte-order position relativeStart.
     // b. S.size = span.
     // c. S.type = relativeContentType.
-    auto byte_buffer = TRY_OR_THROW_OOM(realm().vm(), m_byte_buffer.slice(relative_start, span));
+    auto byte_buffer = TRY_OR_THROW_OOM(vm, m_byte_buffer.slice(relative_start, span));
     return MUST_OR_THROW_OOM(heap().allocate<Blob>(realm(), realm(), move(byte_buffer), move(relative_content_type)));
 }
 
 // https://w3c.github.io/FileAPI/#dom-blob-text
-JS::Promise* Blob::text()
+WebIDL::ExceptionOr<JS::NonnullGCPtr<JS::Promise>> Blob::text()
 {
+    auto& realm = this->realm();
+    auto& vm = realm.vm();
+
     // FIXME: 1. Let stream be the result of calling get stream on this.
     // FIXME: 2. Let reader be the result of getting a reader from stream. If that threw an exception, return a new promise rejected with that exception.
 
     // FIXME: We still need to implement ReadableStream for this step to be fully valid.
     // 3. Let promise be the result of reading all bytes from stream with reader
-    auto promise = JS::Promise::create(realm());
-    auto result = JS::PrimitiveString::create(vm(), DeprecatedString { m_byte_buffer.bytes() });
+    auto promise = JS::Promise::create(realm);
+    auto result = TRY(Bindings::throw_dom_exception_if_needed(vm, [&]() { return JS::PrimitiveString::create(vm, StringView { m_byte_buffer.bytes() }); }));
 
     // 4. Return the result of transforming promise by a fulfillment handler that returns the result of running UTF-8 decode on its first argument.
     promise->fulfill(result);

Userland/Libraries/LibWeb/FileAPI/Blob.h

@@ -1,12 +1,11 @@
 /*
- * Copyright (c) 2022, Kenneth Myhra <kennethmyhra@serenityos.org>
+ * Copyright (c) 2022-2023, Kenneth Myhra <kennethmyhra@serenityos.org>
  *
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
 #include <AK/NonnullRefPtr.h>
 #include <AK/Vector.h>
 #include <LibWeb/Bindings/BlobPrototype.h>
@@ -16,14 +15,14 @@
 
 namespace Web::FileAPI {
 
-using BlobPart = Variant<JS::Handle<JS::Object>, JS::Handle<Blob>, DeprecatedString>;
+using BlobPart = Variant<JS::Handle<JS::Object>, JS::Handle<Blob>, String>;
 
 struct BlobPropertyBag {
-    DeprecatedString type = DeprecatedString::empty();
+    String type = String {};
     Bindings::EndingType endings;
 };
 
-[[nodiscard]] ErrorOr<DeprecatedString> convert_line_endings_to_native(DeprecatedString const& string);
+[[nodiscard]] ErrorOr<String> convert_line_endings_to_native(StringView string);
 [[nodiscard]] ErrorOr<ByteBuffer> process_blob_parts(Vector<BlobPart> const& blob_parts, Optional<BlobPropertyBag> const& options = {});
 [[nodiscard]] bool is_basic_latin(StringView view);
 
@@ -33,24 +32,24 @@ class Blob : public Bindings::PlatformObject {
 public:
     virtual ~Blob() override;
 
-    static WebIDL::ExceptionOr<JS::NonnullGCPtr<Blob>> create(JS::Realm&, ByteBuffer, DeprecatedString type);
+    static WebIDL::ExceptionOr<JS::NonnullGCPtr<Blob>> create(JS::Realm&, ByteBuffer, String type);
     static WebIDL::ExceptionOr<JS::NonnullGCPtr<Blob>> create(JS::Realm&, Optional<Vector<BlobPart>> const& blob_parts = {}, Optional<BlobPropertyBag> const& options = {});
     static WebIDL::ExceptionOr<JS::NonnullGCPtr<Blob>> construct_impl(JS::Realm&, Optional<Vector<BlobPart>> const& blob_parts = {}, Optional<BlobPropertyBag> const& options = {});
 
     // https://w3c.github.io/FileAPI/#dfn-size
     u64 size() const { return m_byte_buffer.size(); }
     // https://w3c.github.io/FileAPI/#dfn-type
-    DeprecatedString const& type() const { return m_type; }
+    String const& type() const { return m_type; }
 
-    WebIDL::ExceptionOr<JS::NonnullGCPtr<Blob>> slice(Optional<i64> start = {}, Optional<i64> end = {}, Optional<DeprecatedString> const& content_type = {});
+    WebIDL::ExceptionOr<JS::NonnullGCPtr<Blob>> slice(Optional<i64> start = {}, Optional<i64> end = {}, Optional<String> const& content_type = {});
 
-    JS::Promise* text();
+    WebIDL::ExceptionOr<JS::NonnullGCPtr<JS::Promise>> text();
     JS::Promise* array_buffer();
 
     ReadonlyBytes bytes() const { return m_byte_buffer.bytes(); }
 
 protected:
-    Blob(JS::Realm&, ByteBuffer, DeprecatedString type);
+    Blob(JS::Realm&, ByteBuffer, String type);
     Blob(JS::Realm&, ByteBuffer);
 
     virtual JS::ThrowCompletionOr<void> initialize(JS::Realm&) override;
@@ -59,7 +58,7 @@ private:
     explicit Blob(JS::Realm&);
 
     ByteBuffer m_byte_buffer {};
-    DeprecatedString m_type {};
+    String m_type {};
 };
 
 }

Userland/Libraries/LibWeb/FileAPI/Blob.idl

@@ -1,4 +1,4 @@
-[Exposed=(Window,Worker), Serializable]
+[Exposed=(Window,Worker), Serializable, UseNewAKString]
 interface Blob {
     constructor(optional sequence<BlobPart> blobParts, optional BlobPropertyBag options = {});
 

Userland/Libraries/LibWeb/FileAPI/File.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2022, Kenneth Myhra <kennethmyhra@serenityos.org>
+ * Copyright (c) 2022-2023, Kenneth Myhra <kennethmyhra@serenityos.org>
  *
  * SPDX-License-Identifier: BSD-2-Clause
  */
@@ -8,10 +8,11 @@
 #include <LibJS/Runtime/Completion.h>
 #include <LibWeb/Bindings/Intrinsics.h>
 #include <LibWeb/FileAPI/File.h>
+#include <LibWeb/Infra/Strings.h>
 
 namespace Web::FileAPI {
 
-File::File(JS::Realm& realm, ByteBuffer byte_buffer, DeprecatedString file_name, DeprecatedString type, i64 last_modified)
+File::File(JS::Realm& realm, ByteBuffer byte_buffer, String file_name, String type, i64 last_modified)
     : Blob(realm, move(byte_buffer), move(type))
     , m_name(move(file_name))
     , m_last_modified(last_modified)
@@ -29,8 +30,10 @@ JS::ThrowCompletionOr<void> File::initialize(JS::Realm& realm)
 File::~File() = default;
 
 // https://w3c.github.io/FileAPI/#ref-for-dom-file-file
-WebIDL::ExceptionOr<JS::NonnullGCPtr<File>> File::create(JS::Realm& realm, Vector<BlobPart> const& file_bits, DeprecatedString const& file_name, Optional<FilePropertyBag> const& options)
+WebIDL::ExceptionOr<JS::NonnullGCPtr<File>> File::create(JS::Realm& realm, Vector<BlobPart> const& file_bits, String const& file_name, Optional<FilePropertyBag> const& options)
 {
+    auto& vm = realm.vm();
+
     // 1. Let bytes be the result of processing blob parts given fileBits and options.
     auto bytes = TRY_OR_THROW_OOM(realm.vm(), process_blob_parts(file_bits, options.has_value() ? static_cast<BlobPropertyBag const&>(*options) : Optional<BlobPropertyBag> {}));
 
@@ -38,7 +41,7 @@ WebIDL::ExceptionOr<JS::NonnullGCPtr<File>> File::create(JS::Realm& realm, Vecto
     //    NOTE: Underlying OS filesystems use differing conventions for file name; with constructed files, mandating UTF-16 lessens ambiquity when file names are converted to byte sequences.
     auto name = file_name;
 
-    auto type = DeprecatedString::empty();
+    auto type = String {};
     i64 last_modified = 0;
     // 3. Process FilePropertyBag dictionary argument by running the following substeps:
     if (options.has_value()) {
@@ -52,7 +55,7 @@ WebIDL::ExceptionOr<JS::NonnullGCPtr<File>> File::create(JS::Realm& realm, Vecto
 
         // 2. Convert every character in t to ASCII lowercase.
         if (!type.is_empty())
-            type = options->type.to_lowercase();
+            type = TRY_OR_THROW_OOM(vm, Infra::to_ascii_lower_case(type));
 
         // 3. If the lastModified member is provided, let d be set to the lastModified dictionary member. If it is not provided, set d to the current date and time represented as the number of milliseconds since the Unix Epoch (which is the equivalent of Date.now() [ECMA-262]).
         //    Note: Since ECMA-262 Date objects convert to long long values representing the number of milliseconds since the Unix Epoch, the lastModified member could be a Date object [ECMA-262].
@@ -69,7 +72,7 @@ WebIDL::ExceptionOr<JS::NonnullGCPtr<File>> File::create(JS::Realm& realm, Vecto
     return MUST_OR_THROW_OOM(realm.heap().allocate<File>(realm, realm, move(bytes), move(name), move(type), last_modified));
 }
 
-WebIDL::ExceptionOr<JS::NonnullGCPtr<File>> File::construct_impl(JS::Realm& realm, Vector<BlobPart> const& file_bits, DeprecatedString const& file_name, Optional<FilePropertyBag> const& options)
+WebIDL::ExceptionOr<JS::NonnullGCPtr<File>> File::construct_impl(JS::Realm& realm, Vector<BlobPart> const& file_bits, String const& file_name, Optional<FilePropertyBag> const& options)
 {
     return create(realm, file_bits, file_name, options);
 }

Userland/Libraries/LibWeb/FileAPI/File.h

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2022, Kenneth Myhra <kennethmyhra@serenityos.org>
+ * Copyright (c) 2022-2023, Kenneth Myhra <kennethmyhra@serenityos.org>
  *
  * SPDX-License-Identifier: BSD-2-Clause
  */
@@ -18,22 +18,22 @@ class File : public Blob {
     WEB_PLATFORM_OBJECT(File, Blob);
 
 public:
-    static WebIDL::ExceptionOr<JS::NonnullGCPtr<File>> create(JS::Realm&, Vector<BlobPart> const& file_bits, DeprecatedString const& file_name, Optional<FilePropertyBag> const& options = {});
-    static WebIDL::ExceptionOr<JS::NonnullGCPtr<File>> construct_impl(JS::Realm&, Vector<BlobPart> const& file_bits, DeprecatedString const& file_name, Optional<FilePropertyBag> const& options = {});
+    static WebIDL::ExceptionOr<JS::NonnullGCPtr<File>> create(JS::Realm&, Vector<BlobPart> const& file_bits, String const& file_name, Optional<FilePropertyBag> const& options = {});
+    static WebIDL::ExceptionOr<JS::NonnullGCPtr<File>> construct_impl(JS::Realm&, Vector<BlobPart> const& file_bits, String const& file_name, Optional<FilePropertyBag> const& options = {});
 
     virtual ~File() override;
 
     // https://w3c.github.io/FileAPI/#dfn-name
-    DeprecatedString const& name() const { return m_name; }
+    String const& name() const { return m_name; }
     // https://w3c.github.io/FileAPI/#dfn-lastModified
     i64 last_modified() const { return m_last_modified; }
 
 private:
-    File(JS::Realm&, ByteBuffer, DeprecatedString file_name, DeprecatedString type, i64 last_modified);
+    File(JS::Realm&, ByteBuffer, String file_name, String type, i64 last_modified);
 
     virtual JS::ThrowCompletionOr<void> initialize(JS::Realm&) override;
 
-    DeprecatedString m_name;
+    String m_name;
     i64 m_last_modified { 0 };
 };
 

Userland/Libraries/LibWeb/FileAPI/File.idl

@@ -1,6 +1,6 @@
 #import <FileAPI/Blob.idl>
 
-[Exposed=(Window,Worker), Serializable]
+[Exposed=(Window,Worker), Serializable, UseNewAKString]
 interface File : Blob {
     constructor(sequence<BlobPart> fileBits, USVString fileName, optional FilePropertyBag options = {});
 

Userland/Libraries/LibWeb/HTML/FormControlInfrastructure.cpp

@@ -36,7 +36,7 @@ WebIDL::ExceptionOr<XHR::FormDataEntry> create_entry(JS::Realm& realm, String co
                 name_attribute = filename.value();
             else
                 name_attribute = TRY_OR_THROW_OOM(vm, "blob"_string);
-            return JS::make_handle(TRY(FileAPI::File::create(realm, { JS::make_handle(*blob) }, name_attribute.to_deprecated_string(), {})));
+            return JS::make_handle(TRY(FileAPI::File::create(realm, { JS::make_handle(*blob) }, move(name_attribute), {})));
         }));
 
     // 4. Return an entry whose name is name and whose value is value.
@@ -130,8 +130,8 @@ WebIDL::ExceptionOr<Optional<Vector<XHR::FormDataEntry>>> construct_entry_list(J
             // 1. If there are no selected files, then create an entry with name and a new File object with an empty name, application/octet-stream as type, and an empty body, and append it to entry list.
             if (file_element->files()->length() == 0) {
                 FileAPI::FilePropertyBag options {};
-                options.type = "application/octet-stream";
-                auto file = TRY(FileAPI::File::create(realm, {}, "", options));
+                options.type = TRY_OR_THROW_OOM(vm, "application/octet-stream"_string);
+                auto file = TRY(FileAPI::File::create(realm, {}, String {}, options));
                 TRY_OR_THROW_OOM(vm, entry_list.try_append(XHR::FormDataEntry { .name = move(name), .value = JS::make_handle(file) }));
             }
             // 2. Otherwise, for each file in selected files, create an entry with name and a File object representing the file, and append it to entry list.

Userland/Libraries/LibWeb/XHR/XMLHttpRequest.cpp

@@ -3,7 +3,7 @@
  * Copyright (c) 2021-2022, Linus Groh <linusg@serenityos.org>
  * Copyright (c) 2022, Luke Wilde <lukew@serenityos.org>
  * Copyright (c) 2022, Ali Mohammad Pur <mpfard@serenityos.org>
- * Copyright (c) 2022, Kenneth Myhra <kennethmyhra@serenityos.org>
+ * Copyright (c) 2022-2023, Kenneth Myhra <kennethmyhra@serenityos.org>
  *
  * SPDX-License-Identifier: BSD-2-Clause
  */
@@ -161,7 +161,8 @@ WebIDL::ExceptionOr<JS::Value> XMLHttpRequest::response()
     }
     // 6. Otherwise, if this’s response type is "blob", set this’s response object to a new Blob object representing this’s received bytes with type set to the result of get a final MIME type for this.
     else if (m_response_type == Bindings::XMLHttpRequestResponseType::Blob) {
-        auto blob_part = TRY(FileAPI::Blob::create(realm(), m_received_bytes, get_final_mime_type().type()));
+        auto mime_type_as_string = TRY_OR_THROW_OOM(vm, String::from_deprecated_string(get_final_mime_type().type()));
+        auto blob_part = TRY(FileAPI::Blob::create(realm(), m_received_bytes, move(mime_type_as_string)));
         auto blob = TRY(FileAPI::Blob::create(realm(), Vector<FileAPI::BlobPart> { JS::make_handle(*blob_part) }));
         m_response_object = JS::Value(blob.ptr());
     }