Add typings for JSDate

.github/workflows/js_interop.yaml

@@ -0,0 +1,41 @@
+name: package:js_interop
+permissions: read-all
+
+on:
+  # Run CI on pushes to the main branch and on PRs.
+  push:
+    branches: [ main ]
+    paths:
+      - '.github/workflows/js_interop.yaml'
+      - 'js_interop/**'
+  pull_request:
+    paths:
+      - '.github/workflows/js_interop.yaml'
+      - 'js_interop/**'
+  schedule:
+    - cron: "0 0 * * 0"
+
+defaults:
+  run:
+    working-directory: js_interop/
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        sdk: [3.9, beta, dev]
+        test_config: ['-p chrome', '-p chrome -c dart2wasm', '-p node']
+
+    steps:
+      - uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8
+      - uses: dart-lang/setup-dart@e51d8e571e22473a2ddebf0ef8a2123f0ab2c02c
+        with:
+          sdk: ${{ matrix.sdk }}
+
+      - run: dart pub get
+      - run: dart format --output=none --set-exit-if-changed .
+        if: ${{ matrix.sdk == 'dev' }}
+      - run: dart analyze --fatal-infos
+      - run: dart test ${{ matrix.test_config }}

js_interop/dart_test.yaml

@@ -0,0 +1 @@
+platforms: [chrome, node]

js_interop/lib/js_interop.dart

@@ -2,4 +2,5 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
+export 'src/dart/date_time.dart';
 export 'src/date.dart';

js_interop/lib/src/dart/date_time.dart

@@ -0,0 +1,10 @@
+// Copyright (c) 2025, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import '../date.dart';
+
+extension DateTimeToJSDate on DateTime {
+  /// Converts this to a [JSDate] that represents the same instant in time.
+  JSDate get toJS => JSDate.fromMillisecondsSinceEpoch(millisecondsSinceEpoch);
+}

js_interop/lib/src/date.dart

@@ -12,7 +12,7 @@ extension type JSDate._(JSObject _) implements JSObject {
   /// The [Date constructor] that returns the current date and time.
   ///
   /// [Date constructor]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Date/Date
-  external JSDate.now();
+  external JSDate.nowAsDate();
 
   /// The [Date constructor] with the number of milliseconds since the epoch of
   /// January 1, 1970, UTC.
@@ -24,20 +24,83 @@ extension type JSDate._(JSObject _) implements JSObject {
   ///
   /// [Date constructor]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Date/Date
   /// [from a string]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Date/Date#date_string
-  external JSDate.parse(String dateString);
+  external JSDate.parseAsDate(String dateString);
 
   /// The [Date constructor] that copies its value [from an existing Date].
   ///
   /// [Date constructor]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Date/Date
   /// [from an existing Date]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Date/Date#date_object
   external JSDate.from(JSDate other);
 
-  /// The [Date constructor] that uses [individual component integers].
+  /// The [Date constructor] that uses [individual component integers],
+  /// interpreted in the local time zone.
   ///
   /// [Date constructor]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Date/Date
   /// [individual component integers]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Date/Date#individual_date_and_time_component_values
-  external JSDate(int year, int month,
-      [int? day, int? hours, int? minutes, int? seconds, int? milliseconds]);
+  external JSDate.localDate(
+    int year,
+    int month, [
+    int? day,
+    int? hours,
+    int? minutes,
+    int? seconds,
+    int? milliseconds,
+  ]);
+
+  /// The [Date constructor] that uses [individual component integers],
+  /// interpreted in the UTC time zone.
+  ///
+  /// [Date constructor]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Date/Date
+  /// [individual component integers]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Date/Date#individual_date_and_time_component_values
+  factory JSDate.utcDate(
+    int year,
+    int month, [
+    int? day,
+    int? hours,
+    int? minutes,
+    int? seconds,
+    int? milliseconds,
+  ]) {
+    var ms = switch ((day, hours, minutes, seconds, milliseconds)) {
+      (_, _, _, _, var milliseconds?) => JSDate.utcAsMillisecondsSinceEpoch(
+        year,
+        month,
+        day,
+        hours,
+        minutes,
+        seconds,
+        milliseconds,
+      ),
+      (_, _, _, var seconds?, _) => JSDate.utcAsMillisecondsSinceEpoch(
+        year,
+        month,
+        day,
+        hours,
+        minutes,
+        seconds,
+      ),
+      (_, _, var minutes?, _, _) => JSDate.utcAsMillisecondsSinceEpoch(
+        year,
+        month,
+        day,
+        hours,
+        minutes,
+      ),
+      (_, var hours?, _, _, _) => JSDate.utcAsMillisecondsSinceEpoch(
+        year,
+        month,
+        day,
+        hours,
+      ),
+      (var day?, _, _, _, _) => JSDate.utcAsMillisecondsSinceEpoch(
+        year,
+        month,
+        day,
+      ),
+      _ => JSDate.utcAsMillisecondsSinceEpoch(year, month),
+    };
+    return JSDate.fromMillisecondsSinceEpoch(ms);
+  }
 
   /// Dee [`Date.now()`].
   ///
@@ -55,13 +118,15 @@ extension type JSDate._(JSObject _) implements JSObject {
   ///
   /// [`Date.utc()`]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Date/UTC
   @JS('UTC')
-  external static int utc(int year,
-      [int? month,
-      int? day,
-      int? hours,
-      int? minutes,
-      int? seconds,
-      int? milliseconds]);
+  external static int utcAsMillisecondsSinceEpoch(
+    int year, [
+    int? month,
+    int? day,
+    int? hours,
+    int? minutes,
+    int? seconds,
+    int? milliseconds,
+  ]);
 
   /// See [`Date.getDate()`] and [`Date.setDate()`].
   ///
@@ -81,14 +146,10 @@ extension type JSDate._(JSObject _) implements JSObject {
   /// [`Date.getDay()`]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Date/getDay
   /// [`Date.setDay()`]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Date/setDay
   int get day => _getDay();
-  set day(int value) => _setDay(value);
 
   @JS('getDay')
   external int _getDay();
 
-  @JS('setDay')
-  external void _setDay(int value);
-
   /// See [`Date.getFullYear()`] and [`Date.setFullYear()`].
   ///
   /// [`Date.getFullYear()`]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Date/getFullYear

js_interop/pubspec.yaml

@@ -5,3 +5,6 @@ repository: https://github.com/dart-lang/web
 
 environment:
   sdk: ^3.9.0
+
+dev_dependencies:
+  test: ^1.26.0