ReadableStream

src/browser/ScriptManager.zig

@@ -752,11 +752,7 @@ const Script = struct {
         };
 
         if (comptime IS_DEBUG) {
-            log.debug(.browser, "executed script", .{
+            log.debug(.browser, "executed script", .{ .src = url, .success = success, .on_load = script_element._on_load != null });
-                .src = url,
-                .success = success,
-                .on_load = script_element._on_load != null
-            });
         }
 
         defer page.tick();

src/browser/js/Context.zig

@@ -838,7 +838,6 @@ fn jsValueToStruct(self: *Context, comptime T: type, js_value: v8.Value) !?T {
         return .{ .string = try self.valueToString(js_value, .{ .allocator = self.arena }) };
     }
 
-
     if (comptime T == js.Value) {
         // Caller wants an opaque js.Object. Probably a parameter
         // that it needs to pass back into a callback
@@ -1157,15 +1156,14 @@ pub fn stackTrace(self: *const Context) !?[]const u8 {
 }
 
 // == Promise Helpers ==
-pub fn rejectPromise(self: *Context, value: anytype) js.Promise {
+pub fn rejectPromise(self: *Context, value: anytype) !js.Promise {
     const ctx = self.v8_context;
     var resolver = v8.PromiseResolver.init(ctx);
-    if (self.zigValueToJs(value, .{})) |js_value| {
+    const js_value = try self.zigValueToJs(value, .{});
-        _ = resolver.reject(ctx, js_value);
+    if (resolver.reject(ctx, js_value) == null) {
-    } else |err| {
+        return error.FailedToResolvePromise;
-        const str = self.isolate.initStringUtf8(@errorName(err));
-        _ = resolver.reject(ctx, str.toValue());
     }
+    self.runMicrotasks();
     return resolver.getPromise();
 }
 
@@ -1174,7 +1172,10 @@ pub fn resolvePromise(self: *Context, value: anytype) !js.Promise {
     const js_value = try self.zigValueToJs(value, .{});
 
     var resolver = v8.PromiseResolver.init(ctx);
-    _ = resolver.resolve(ctx, js_value);
+    if (resolver.resolve(ctx, js_value) == null) {
+        return error.FailedToResolvePromise;
+    }
+    self.runMicrotasks();
 
     return resolver.getPromise();
 }
@@ -1257,12 +1258,12 @@ pub fn dynamicModuleCallback(
 
     const resource = self.jsStringToZigZ(.{ .handle = resource_name.? }, .{}) catch |err| {
         log.err(.app, "OOM", .{ .err = err, .src = "dynamicModuleCallback1" });
-        return @constCast(self.rejectPromise("Out of memory").handle);
+        return @constCast((self.rejectPromise("Out of memory") catch return null).handle);
     };
 
     const specifier = self.jsStringToZigZ(.{ .handle = v8_specifier.? }, .{}) catch |err| {
         log.err(.app, "OOM", .{ .err = err, .src = "dynamicModuleCallback2" });
-        return @constCast(self.rejectPromise("Out of memory").handle);
+        return @constCast((self.rejectPromise("Out of memory") catch return null).handle);
     };
 
     const normalized_specifier = self.script_manager.?.resolveSpecifier(
@@ -1271,14 +1272,14 @@ pub fn dynamicModuleCallback(
         specifier,
     ) catch |err| {
         log.err(.app, "OOM", .{ .err = err, .src = "dynamicModuleCallback3" });
-        return @constCast(self.rejectPromise("Out of memory").handle);
+        return @constCast((self.rejectPromise("Out of memory") catch return null).handle);
     };
 
     const promise = self._dynamicModuleCallback(normalized_specifier, resource) catch |err| blk: {
         log.err(.js, "dynamic module callback", .{
             .err = err,
         });
-        break :blk self.rejectPromise("Failed to load module");
+        break :blk self.rejectPromise("Failed to load module") catch return null;
     };
     return @constCast(promise.handle);
 }

src/browser/js/Env.zig

@@ -270,7 +270,10 @@ pub fn attachClass(comptime JsApi: type, isolate: v8.Isolate, template: v8.Funct
             bridge.Iterator => {
                 // Same as a function, but with a specific name
                 const function_template = v8.FunctionTemplate.initCallback(isolate, value.func);
-                const js_name = v8.Symbol.getIterator(isolate).toName();
+                const js_name = if (value.async)
+                    v8.Symbol.getAsyncIterator(isolate).toName()
+                else
+                    v8.Symbol.getIterator(isolate).toName();
                 template_proto.set(js_name, function_template, v8.PropertyAttribute.None);
             },
             bridge.Property => {

src/browser/js/bridge.zig

@@ -284,28 +284,36 @@ pub const NamedIndexed = struct {
 
 pub const Iterator = struct {
     func: *const fn (?*const v8.C_FunctionCallbackInfo) callconv(.c) void,
+    async: bool,
 
-    const Opts = struct {};
+    const Opts = struct {
+        async: bool = false,
+    };
 
     fn init(comptime T: type, comptime struct_or_func: anytype, comptime opts: Opts) Iterator {
-        _ = opts;
         if (@typeInfo(@TypeOf(struct_or_func)) == .type) {
-            return .{ .func = struct {
+            return .{
+                .async = opts.async,
+                .func = struct {
                     fn wrap(raw_info: ?*const v8.C_FunctionCallbackInfo) callconv(.c) void {
                         const info = v8.FunctionCallbackInfo.initFromV8(raw_info);
                         info.getReturnValue().set(info.getThis());
                     }
-            }.wrap };
+                }.wrap,
+            };
         }
 
-        return .{ .func = struct {
+        return .{
+            .async = opts.async,
+            .func = struct {
                 fn wrap(raw_info: ?*const v8.C_FunctionCallbackInfo) callconv(.c) void {
                     const info = v8.FunctionCallbackInfo.initFromV8(raw_info);
                     var caller = Caller.init(info);
                     defer caller.deinit();
                     caller.method(T, struct_or_func, info, .{});
                 }
-        }.wrap };
+            }.wrap,
+        };
     }
 };
 
@@ -564,6 +572,9 @@ pub const JsApis = flattenTypes(&.{
     @import("../webapi/net/URLSearchParams.zig"),
     @import("../webapi/net/XMLHttpRequest.zig"),
     @import("../webapi/net/XMLHttpRequestEventTarget.zig"),
+    @import("../webapi/streams/ReadableStream.zig"),
+    @import("../webapi/streams/ReadableStreamDefaultReader.zig"),
+    @import("../webapi/streams/ReadableStreamDefaultController.zig"),
     @import("../webapi/Node.zig"),
     @import("../webapi/storage/storage.zig"),
     @import("../webapi/URL.zig"),

src/browser/tests/streams/readable_stream.html

@@ -0,0 +1,192 @@
+<!DOCTYPE html>
+<script src="../testing.js"></script>
+<script id=readable_stream_basic>
+  {
+    // Test basic stream creation
+    const stream = new ReadableStream();
+    testing.expectEqual('object', typeof stream);
+    testing.expectEqual('function', typeof stream.getReader);
+  }
+</script>
+
+<script id=readable_stream_reader>
+  {
+    // Test getting a reader
+    const stream = new ReadableStream();
+    const reader = stream.getReader();
+    testing.expectEqual('object', typeof reader);
+    testing.expectEqual('function', typeof reader.read);
+    testing.expectEqual('function', typeof reader.releaseLock);
+    testing.expectEqual('function', typeof reader.cancel);
+  }
+</script>
+
+<script id=readable_stream_read_empty>
+  (async function() {
+    const stream = new ReadableStream();
+    const reader = stream.getReader();
+
+    // Reading from empty stream should return done:true
+    const result = await reader.read();
+    testing.expectEqual('object', typeof result);
+    testing.expectEqual(true, result.done);
+  })();
+</script>
+
+<script id=response_body>
+  (async function() {
+    const response = new Response('hello world');
+    testing.expectEqual('object', typeof response.body);
+
+    const reader = response.body.getReader();
+    const result = await reader.read();
+
+    testing.expectEqual(false, result.done);
+    testing.expectEqual(true, result.value instanceof Uint8Array);
+
+    // Convert Uint8Array to string
+    const decoder = new TextDecoder();
+    const text = decoder.decode(result.value);
+    testing.expectEqual('hello world', text);
+
+    // Next read should be done
+    const result2 = await reader.read();
+    testing.expectEqual(true, result2.done);
+  })();
+</script>
+
+<script id=response_text>
+  (async function() {
+    const response = new Response('hello from text()');
+    const text = await response.text();
+    testing.expectEqual('hello from text()', text);
+  })();
+</script>
+
+<script id=response_json>
+  (async function() {
+    const response = new Response('{"foo":"bar","num":42}');
+    const json = await response.json();
+    testing.expectEqual('object', typeof json);
+    testing.expectEqual('bar', json.foo);
+    testing.expectEqual(42, json.num);
+  })();
+</script>
+
+<script id=response_null_body>
+  {
+    // Response with no body should have null body
+    const response = new Response();
+    testing.expectEqual(null, response.body);
+  }
+</script>
+
+<script id=response_empty_string_body>
+  (async function() {
+    // Response with empty string should have a stream that's immediately closed
+    const response = new Response('');
+    testing.expectEqual('object', typeof response.body);
+
+    const reader = response.body.getReader();
+    const result = await reader.read();
+
+    // Stream should be closed immediately (done: true, no value)
+    testing.expectEqual(true, result.done);
+  })();
+</script>
+
+<script id=response_status>
+  (async function() {
+    const response = new Response('test', { status: 404 });
+    testing.expectEqual(404, response.status);
+    testing.expectEqual(false, response.ok);
+
+    const text = await response.text();
+    testing.expectEqual('test', text);
+  })();
+</script>
+
+<script id=async_iterator_exists>
+  (async function() {
+    const stream = new ReadableStream();
+    testing.expectEqual('function', typeof stream[Symbol.asyncIterator]);
+  })();
+</script>
+
+<script id=async_iterator_basic>
+  (async function() {
+    const stream = new ReadableStream();
+    const iterator = stream[Symbol.asyncIterator]();
+    testing.expectEqual('object', typeof iterator);
+    testing.expectEqual('function', typeof iterator.next);
+  })();
+</script>
+
+<script id=async_iterator_for_await>
+  (async function() {
+    const response = new Response('test data');
+    const stream = response.body;
+
+    const chunks = [];
+    for await (const chunk of stream) {
+      chunks.push(chunk);
+    }
+
+    testing.expectEqual(1, chunks.length);
+    testing.expectEqual(true, chunks[0] instanceof Uint8Array);
+
+    const decoder = new TextDecoder();
+    const text = decoder.decode(chunks[0]);
+    testing.expectEqual('test data', text);
+  })();
+</script>
+
+<script id=async_iterator_locks_stream>
+  (async function() {
+    const response = new Response('test');
+    const stream = response.body;
+
+    // Get async iterator (locks stream)
+    const iterator = stream[Symbol.asyncIterator]();
+
+    // Try to get reader - should fail
+    let errorThrown = false;
+    try {
+      stream.getReader();
+    } catch (e) {
+      errorThrown = true;
+    }
+    testing.expectEqual(true, errorThrown);
+  })();
+</script>
+
+<script id=async_iterator_manual_next>
+  (async function() {
+    const response = new Response('hello');
+    const stream = response.body;
+    const iterator = stream[Symbol.asyncIterator]();
+
+    const result = await iterator.next();
+    testing.expectEqual('object', typeof result);
+    testing.expectEqual(false, result.done);
+    testing.expectEqual(true, result.value instanceof Uint8Array);
+
+    // Second call should be done
+    const result2 = await iterator.next();
+    testing.expectEqual(true, result2.done);
+  })();
+</script>
+
+<script id=async_iterator_early_break>
+  (async function() {
+    const response = new Response('test data');
+    const stream = response.body;
+
+    for await (const chunk of stream) {
+      break; // Early exit
+    }
+
+    // Should not throw errors
+    testing.expectEqual('object', typeof stream);
+  })();
+</script>

src/browser/webapi/MessageChannel.zig

@@ -37,7 +37,6 @@ pub fn init(page: *Page) !*MessageChannel {
     });
 }
 
-
 pub fn getPort1(self: *const MessageChannel) *MessagePort {
     return self._port1;
 }

src/browser/webapi/Window.zig

@@ -271,7 +271,6 @@ pub fn postMessage(self: *Window, message: js.Object, target_origin: ?[]const u8
     });
     errdefer page._factory.destroy(callback);
 
-
     try page.scheduler.add(callback, PostMessageCallback.run, 0, .{
         .name = "postMessage",
         .low_priority = false,

src/browser/webapi/net/Response.zig

@@ -21,6 +21,7 @@ const js = @import("../../js/js.zig");
 
 const Page = @import("../../Page.zig");
 const Headers = @import("Headers.zig");
+const ReadableStream = @import("../streams/ReadableStream.zig");
 const Allocator = std.mem.Allocator;
 
 const Response = @This();
@@ -28,7 +29,7 @@ const Response = @This();
 _status: u16,
 _arena: Allocator,
 _headers: *Headers,
-_body: []const u8,
+_body: ?[]const u8,
 
 const InitOpts = struct {
     status: u16 = 200,
@@ -39,10 +40,13 @@ const InitOpts = struct {
 pub fn init(body_: ?[]const u8, opts_: ?InitOpts, page: *Page) !*Response {
     const opts = opts_ orelse InitOpts{};
 
+    // Store empty string as empty string, not null
+    const body = if (body_) |b| try page.arena.dupe(u8, b) else null;
+
     return page._factory.create(Response{
         ._arena = page.arena,
         ._status = opts.status,
-        ._body = if (body_) |b| try page.arena.dupe(u8, b) else "",
+        ._body = body,
         ._headers = opts.headers orelse try Headers.init(page),
     });
 }
@@ -55,15 +59,34 @@ pub fn getHeaders(self: *const Response) *Headers {
     return self._headers;
 }
 
+pub fn getBody(self: *const Response, page: *Page) !?*ReadableStream {
+    const body = self._body orelse return null;
+
+    // Empty string should create a closed stream with no data
+    if (body.len == 0) {
+        const stream = try ReadableStream.init(page);
+        try stream._controller.close();
+        return stream;
+    }
+
+    return ReadableStream.initWithData(body, page);
+}
+
 pub fn isOK(self: *const Response) bool {
     return self._status >= 200 and self._status <= 299;
 }
 
+pub fn getText(self: *const Response, page: *Page) !js.Promise {
+    const body = self._body orelse "";
+    return page.js.resolvePromise(body);
+}
+
 pub fn getJson(self: *Response, page: *Page) !js.Promise {
+    const body = self._body orelse "";
     const value = std.json.parseFromSliceLeaky(
         std.json.Value,
         page.call_arena,
-        self._body,
+        body,
         .{},
     ) catch |err| {
         return page.js.rejectPromise(.{@errorName(err)});
@@ -83,6 +106,8 @@ pub const JsApi = struct {
     pub const constructor = bridge.constructor(Response.init, .{});
     pub const ok = bridge.accessor(Response.isOK, null, .{});
     pub const status = bridge.accessor(Response.getStatus, null, .{});
+    pub const text = bridge.function(Response.getText, .{});
     pub const json = bridge.function(Response.getJson, .{});
     pub const headers = bridge.accessor(Response.getHeaders, null, .{});
+    pub const body = bridge.accessor(Response.getBody, null, .{});
 };

src/browser/webapi/net/URLSearchParams.zig

@@ -51,7 +51,7 @@ pub fn init(opts_: ?InitOpts, page: *Page) !*URLSearchParams {
                     break :blk try paramsFromString(arena, try js_val.toString(arena), &page.buf);
                 }
                 return error.InvalidArgument;
-            }
+            },
         }
     };
 

src/browser/webapi/streams/ReadableStream.zig

@@ -0,0 +1,140 @@
+// Copyright (C) 2023-2025  Lightpanda (Selecy SAS)
+//
+// Francis Bouvier <francis@lightpanda.io>
+// Pierre Tachoire <pierre@lightpanda.io>
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as
+// published by the Free Software Foundation, either version 3 of the
+// License, or (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+const std = @import("std");
+const js = @import("../../js/js.zig");
+
+const Page = @import("../../Page.zig");
+const ReadableStreamDefaultReader = @import("ReadableStreamDefaultReader.zig");
+const ReadableStreamDefaultController = @import("ReadableStreamDefaultController.zig");
+
+pub fn registerTypes() []const type {
+    return &.{
+        ReadableStream,
+        AsyncIterator,
+    };
+}
+
+const ReadableStream = @This();
+
+pub const State = enum {
+    readable,
+    closed,
+    errored,
+};
+
+_page: *Page,
+_state: State,
+_reader: ?*ReadableStreamDefaultReader,
+_controller: *ReadableStreamDefaultController,
+_stored_error: ?[]const u8,
+
+pub fn init(page: *Page) !*ReadableStream {
+    const stream = try page._factory.create(ReadableStream{
+        ._page = page,
+        ._state = .readable,
+        ._reader = null,
+        ._controller = undefined,
+        ._stored_error = null,
+    });
+
+    stream._controller = try ReadableStreamDefaultController.init(stream, page);
+    return stream;
+}
+
+pub fn initWithData(data: []const u8, page: *Page) !*ReadableStream {
+    const stream = try init(page);
+
+    // For Phase 1: immediately enqueue all data and close
+    try stream._controller.enqueue(data);
+    try stream._controller.close();
+
+    return stream;
+}
+
+pub fn getReader(self: *ReadableStream, page: *Page) !*ReadableStreamDefaultReader {
+    if (self._reader != null) {
+        return error.ReaderLocked;
+    }
+
+    const reader = try ReadableStreamDefaultReader.init(self, page);
+    self._reader = reader;
+    return reader;
+}
+
+pub fn releaseReader(self: *ReadableStream) void {
+    self._reader = null;
+}
+
+pub fn getAsyncIterator(self: *ReadableStream, page: *Page) !*AsyncIterator {
+    return AsyncIterator.init(self, page);
+}
+
+pub const JsApi = struct {
+    pub const bridge = js.Bridge(ReadableStream);
+
+    pub const Meta = struct {
+        pub const name = "ReadableStream";
+        pub const prototype_chain = bridge.prototypeChain();
+        pub var class_id: bridge.ClassId = undefined;
+    };
+
+    pub const constructor = bridge.constructor(ReadableStream.init, .{});
+    pub const getReader = bridge.function(ReadableStream.getReader, .{});
+    pub const symbol_async_iterator = bridge.iterator(ReadableStream.getAsyncIterator, .{ .async = true });
+};
+
+pub const AsyncIterator = struct {
+    _stream: *ReadableStream,
+    _reader: *ReadableStreamDefaultReader,
+
+    pub fn init(stream: *ReadableStream, page: *Page) !*AsyncIterator {
+        const reader = try stream.getReader(page);
+        return page._factory.create(AsyncIterator{
+            ._reader = reader,
+            ._stream = stream,
+        });
+    }
+
+    pub fn next(self: *AsyncIterator, page: *Page) !js.Promise {
+        return self._reader.read(page);
+    }
+
+    pub fn @"return"(self: *AsyncIterator, page: *Page) !js.Promise {
+        self._reader.releaseLock();
+        return page.js.resolvePromise(.{ .done = true, .value = null });
+    }
+
+    pub const JsApi = struct {
+        pub const bridge = js.Bridge(ReadableStream.AsyncIterator);
+
+        pub const Meta = struct {
+            pub const name = "ReadableStreamAsyncIterator";
+            pub const prototype_chain = bridge.prototypeChain();
+            pub var class_id: bridge.ClassId = undefined;
+        };
+
+        pub const next = bridge.function(ReadableStream.AsyncIterator.next, .{});
+        pub const @"return" = bridge.function(ReadableStream.AsyncIterator.@"return", .{});
+    };
+};
+
+const testing = @import("../../../testing.zig");
+test "WebApi: ReadableStream" {
+    try testing.htmlRunner("streams/readable_stream.html", .{});
+}

src/browser/webapi/streams/ReadableStreamDefaultController.zig

@@ -0,0 +1,100 @@
+// Copyright (C) 2023-2025  Lightpanda (Selecy SAS)
+//
+// Francis Bouvier <francis@lightpanda.io>
+// Pierre Tachoire <pierre@lightpanda.io>
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as
+// published by the Free Software Foundation, either version 3 of the
+// License, or (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+const std = @import("std");
+const js = @import("../../js/js.zig");
+
+const Page = @import("../../Page.zig");
+const ReadableStream = @import("ReadableStream.zig");
+
+const ReadableStreamDefaultController = @This();
+
+_page: *Page,
+_stream: *ReadableStream,
+_arena: std.mem.Allocator,
+_queue: std.ArrayList([]const u8),
+
+pub fn init(stream: *ReadableStream, page: *Page) !*ReadableStreamDefaultController {
+    return page._factory.create(ReadableStreamDefaultController{
+        ._page = page,
+        ._stream = stream,
+        ._arena = page.arena,
+        ._queue = std.ArrayList([]const u8){},
+    });
+}
+
+pub fn enqueue(self: *ReadableStreamDefaultController, chunk: []const u8) !void {
+    if (self._stream._state != .readable) {
+        return error.StreamNotReadable;
+    }
+
+    // Store a copy of the chunk in the page arena
+    const chunk_copy = try self._page.arena.dupe(u8, chunk);
+    try self._queue.append(self._arena, chunk_copy);
+}
+
+pub fn close(self: *ReadableStreamDefaultController) !void {
+    if (self._stream._state != .readable) {
+        return error.StreamNotReadable;
+    }
+
+    self._stream._state = .closed;
+}
+
+pub fn doError(self: *ReadableStreamDefaultController, err: []const u8) !void {
+    if (self._stream._state != .readable) {
+        return;
+    }
+
+    self._stream._state = .errored;
+    self._stream._stored_error = try self._page.arena.dupe(u8, err);
+}
+
+pub fn dequeue(self: *ReadableStreamDefaultController) ?[]const u8 {
+    if (self._queue.items.len == 0) {
+        return null;
+    }
+    return self._queue.orderedRemove(0);
+}
+
+pub fn getDesiredSize(self: *const ReadableStreamDefaultController) ?i32 {
+    switch (self._stream._state) {
+        .errored => return null,
+        .closed => return 0,
+        .readable => {
+            // For now, just report based on queue size
+            // In a real implementation, this would use highWaterMark
+            return @as(i32, 1) - @as(i32, @intCast(self._queue.items.len));
+        },
+    }
+}
+
+pub const JsApi = struct {
+    pub const bridge = js.Bridge(ReadableStreamDefaultController);
+
+    pub const Meta = struct {
+        pub const name = "ReadableStreamDefaultController";
+        pub const prototype_chain = bridge.prototypeChain();
+        pub var class_id: bridge.ClassId = undefined;
+    };
+
+    pub const enqueue = bridge.function(ReadableStreamDefaultController.enqueue, .{});
+    pub const close = bridge.function(ReadableStreamDefaultController.close, .{});
+    pub const @"error" = bridge.function(ReadableStreamDefaultController.doError, .{});
+    pub const desiredSize = bridge.accessor(ReadableStreamDefaultController.getDesiredSize, null, .{});
+};

src/browser/webapi/streams/ReadableStreamDefaultReader.zig

@@ -0,0 +1,107 @@
+// Copyright (C) 2023-2025  Lightpanda (Selecy SAS)
+//
+// Francis Bouvier <francis@lightpanda.io>
+// Pierre Tachoire <pierre@lightpanda.io>
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as
+// published by the Free Software Foundation, either version 3 of the
+// License, or (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+const std = @import("std");
+const js = @import("../../js/js.zig");
+
+const Page = @import("../../Page.zig");
+const ReadableStream = @import("ReadableStream.zig");
+
+const ReadableStreamDefaultReader = @This();
+
+_page: *Page,
+_stream: ?*ReadableStream,
+
+pub fn init(stream: *ReadableStream, page: *Page) !*ReadableStreamDefaultReader {
+    return page._factory.create(ReadableStreamDefaultReader{
+        ._stream = stream,
+        ._page = page,
+    });
+}
+
+pub const ReadResult = struct {
+    done: bool,
+    value: ?js.TypedArray(u8),
+};
+
+pub fn read(self: *ReadableStreamDefaultReader, page: *Page) !js.Promise {
+    const stream = self._stream orelse {
+        return page.js.rejectPromise("Reader has been released");
+    };
+
+    if (stream._state == .errored) {
+        const err = stream._stored_error orelse "Stream errored";
+        return page.js.rejectPromise(err);
+    }
+
+    if (stream._controller.dequeue()) |chunk| {
+        const result = ReadResult{
+            .done = false,
+            .value = js.TypedArray(u8){ .values = chunk },
+        };
+        return page.js.resolvePromise(result);
+    }
+
+    if (stream._state == .closed) {
+        const result = ReadResult{
+            .value = null,
+            .done = true,
+        };
+        return page.js.resolvePromise(result);
+    }
+
+    const result = ReadResult{
+        .done = true,
+        .value = null,
+    };
+    return page.js.resolvePromise(result);
+}
+
+pub fn releaseLock(self: *ReadableStreamDefaultReader) void {
+    if (self._stream) |stream| {
+        stream.releaseReader();
+        self._stream = null;
+    }
+}
+
+pub fn cancel(self: *ReadableStreamDefaultReader, reason_: ?[]const u8, page: *Page) !js.Promise {
+    const stream = self._stream orelse {
+        return page.js.rejectPromise("Reader has been released");
+    };
+
+    const reason = reason_ orelse "canceled";
+
+    try stream._controller.doError(reason);
+    self.releaseLock();
+
+    return page.js.resolvePromise(.{});
+}
+
+pub const JsApi = struct {
+    pub const bridge = js.Bridge(ReadableStreamDefaultReader);
+
+    pub const Meta = struct {
+        pub const name = "ReadableStreamDefaultReader";
+        pub const prototype_chain = bridge.prototypeChain();
+        pub var class_id: bridge.ClassId = undefined;
+    };
+
+    pub const read = bridge.function(ReadableStreamDefaultReader.read, .{});
+    pub const cancel = bridge.function(ReadableStreamDefaultReader.cancel, .{});
+    pub const releaseLock = bridge.function(ReadableStreamDefaultReader.releaseLock, .{});
+};