LibJS: Implement Temporal.Duration.prototype.blank

Userland/Libraries/LibJS/Runtime/CommonPropertyNames.h

@@ -71,6 +71,7 @@ namespace JS {
     P(atanh)                                 \
     P(big)                                   \
     P(bind)                                  \
+    P(blank)                                 \
     P(blink)                                 \
     P(bold)                                  \
     P(buffer)                                \

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

@@ -36,6 +36,7 @@ void DurationPrototype::initialize(GlobalObject& global_object)
     define_native_accessor(vm.names.microseconds, microseconds_getter, {}, Attribute::Configurable);
     define_native_accessor(vm.names.nanoseconds, nanoseconds_getter, {}, Attribute::Configurable);
     define_native_accessor(vm.names.sign, sign_getter, {}, Attribute::Configurable);
+    define_native_accessor(vm.names.blank, blank_getter, {}, Attribute::Configurable);
 }
 
 static Duration* typed_this(GlobalObject& global_object)
@@ -194,4 +195,24 @@ JS_DEFINE_NATIVE_FUNCTION(DurationPrototype::sign_getter)
     return Value(duration_sign(duration->years(), duration->months(), duration->weeks(), duration->days(), duration->hours(), duration->minutes(), duration->seconds(), duration->milliseconds(), duration->microseconds(), duration->nanoseconds()));
 }
 
+// 7.3.14 get Temporal.Duration.prototype.blank, https://tc39.es/proposal-temporal/#sec-get-temporal.duration.prototype.blank
+JS_DEFINE_NATIVE_FUNCTION(DurationPrototype::blank_getter)
+{
+    // 1. Let duration be the this value.
+    // 2. Perform ? RequireInternalSlot(duration, [[InitializedTemporalDuration]]).
+    auto* duration = typed_this(global_object);
+    if (vm.exception())
+        return {};
+
+    // 3. Let sign be ! DurationSign(duration.[[Years]], duration.[[Months]], duration.[[Weeks]], duration.[[Days]], duration.[[Hours]], duration.[[Minutes]], duration.[[Seconds]], duration.[[Milliseconds]], duration.[[Microseconds]], duration.[[Nanoseconds]]).
+    auto sign = duration_sign(duration->years(), duration->months(), duration->weeks(), duration->days(), duration->hours(), duration->minutes(), duration->seconds(), duration->milliseconds(), duration->microseconds(), duration->nanoseconds());
+
+    // 4. If sign = 0, return true.
+    if (sign == 0)
+        return Value(true);
+
+    // 5. Return false.
+    return Value(false);
+}
+
 }

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

@@ -30,6 +30,7 @@ private:
     JS_DECLARE_NATIVE_FUNCTION(microseconds_getter);
     JS_DECLARE_NATIVE_FUNCTION(nanoseconds_getter);
     JS_DECLARE_NATIVE_FUNCTION(sign_getter);
+    JS_DECLARE_NATIVE_FUNCTION(blank_getter);
 };
 
 }

Userland/Libraries/LibJS/Tests/builtins/Temporal/Duration/Duration.prototype.blank.js

@@ -0,0 +1,17 @@
+describe("correct behavior", () => {
+    test("basic functionality", () => {
+        const nonBlankDuration = new Temporal.Duration(123);
+        expect(nonBlankDuration.blank).toBeFalse();
+
+        const blankDuration = new Temporal.Duration(0);
+        expect(blankDuration.blank).toBeTrue();
+    });
+});
+
+test("errors", () => {
+    test("this value must be a Temporal.Duration object", () => {
+        expect(() => {
+            Reflect.get(Temporal.Duration.prototype, "blank", "foo");
+        }).toThrowWithMessage(TypeError, "Not a Temporal.Duration");
+    });
+});