LibJS: Implement Temporal.ZonedDateTime.prototype.toPlainDateTime()

Userland/Libraries/LibJS/Runtime/Temporal/ZonedDateTimePrototype.cpp

@@ -64,6 +64,7 @@ void ZonedDateTimePrototype::initialize(GlobalObject& global_object)
     define_native_function(vm.names.toInstant, to_instant, 0, attr);
     define_native_function(vm.names.toPlainDate, to_plain_date, 0, attr);
     define_native_function(vm.names.toPlainTime, to_plain_time, 0, attr);
+    define_native_function(vm.names.toPlainDateTime, to_plain_date_time, 0, attr);
 }
 
 static ZonedDateTime* typed_this(GlobalObject& global_object)
@@ -772,4 +773,23 @@ JS_DEFINE_NATIVE_FUNCTION(ZonedDateTimePrototype::to_plain_time)
     return create_temporal_time(global_object, temporal_date_time->iso_hour(), temporal_date_time->iso_minute(), temporal_date_time->iso_second(), temporal_date_time->iso_millisecond(), temporal_date_time->iso_microsecond(), temporal_date_time->iso_nanosecond());
 }
 
+// 6.3.49 Temporal.ZonedDateTime.prototype.toPlainDateTime ( ), https://tc39.es/proposal-temporal/#sec-temporal.zoneddatetime.prototype.toplaindatetime
+JS_DEFINE_NATIVE_FUNCTION(ZonedDateTimePrototype::to_plain_date_time)
+{
+    // 1. Let zonedDateTime be the this value.
+    // 2. Perform ? RequireInternalSlot(zonedDateTime, [[InitializedTemporalZonedDateTime]]).
+    auto* zoned_date_time = typed_this(global_object);
+    if (vm.exception())
+        return {};
+
+    // 3. Let timeZone be zonedDateTime.[[TimeZone]].
+    auto& time_zone = zoned_date_time->time_zone();
+
+    // 4. Let instant be ! CreateTemporalInstant(zonedDateTime.[[Nanoseconds]]).
+    auto* instant = create_temporal_instant(global_object, zoned_date_time->nanoseconds());
+
+    // 5. Return ? BuiltinTimeZoneGetPlainDateTimeFor(timeZone, instant, zonedDateTime.[[Calendar]]).
+    return builtin_time_zone_get_plain_date_time_for(global_object, &time_zone, *instant, zoned_date_time->calendar());
+}
+
 }

Userland/Libraries/LibJS/Runtime/Temporal/ZonedDateTimePrototype.h

@@ -49,6 +49,7 @@ private:
     JS_DECLARE_NATIVE_FUNCTION(to_instant);
     JS_DECLARE_NATIVE_FUNCTION(to_plain_date);
     JS_DECLARE_NATIVE_FUNCTION(to_plain_time);
+    JS_DECLARE_NATIVE_FUNCTION(to_plain_date_time);
 };
 
 }

Userland/Libraries/LibJS/Tests/builtins/Temporal/ZonedDateTime/ZonedDateTime.prototype.toPlainDateTime.js

@@ -0,0 +1,29 @@
+describe("correct behavior", () => {
+    test("length is 0", () => {
+        expect(Temporal.ZonedDateTime.prototype.toPlainDateTime).toHaveLength(0);
+    });
+
+    test("basic functionality", () => {
+        const timeZone = new Temporal.TimeZone("UTC");
+        const zonedDateTime = new Temporal.ZonedDateTime(1625614921000000000n, timeZone);
+        const plainDateTime = zonedDateTime.toPlainDateTime();
+        expect(plainDateTime).toBeInstanceOf(Temporal.PlainDateTime);
+        expect(plainDateTime.year).toBe(2021);
+        expect(plainDateTime.month).toBe(7);
+        expect(plainDateTime.day).toBe(6);
+        expect(plainDateTime.hour).toBe(23);
+        expect(plainDateTime.minute).toBe(42);
+        expect(plainDateTime.second).toBe(1);
+        expect(plainDateTime.millisecond).toBe(0);
+        expect(plainDateTime.microsecond).toBe(0);
+        expect(plainDateTime.nanosecond).toBe(0);
+    });
+});
+
+test("errors", () => {
+    test("this value must be a Temporal.ZonedDateTime object", () => {
+        expect(() => {
+            Temporal.ZonedDateTime.prototype.toPlainDateTime.call("foo");
+        }).toThrowWithMessage(TypeError, "Not a Temporal.ZonedDateTime");
+    });
+});