LibJS: Start implementing the stage 3 Intl.DurationFormat proposal

Userland/Libraries/LibJS/Runtime/Intl/DurationFormat.cpp

@@ -0,0 +1,182 @@
+/*
+ * Copyright (c) 2022, Idan Horowitz <idan.horowitz@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <LibJS/Runtime/GlobalObject.h>
+#include <LibJS/Runtime/Intl/AbstractOperations.h>
+#include <LibJS/Runtime/Intl/DurationFormat.h>
+
+namespace JS::Intl {
+
+// 1 DurationFormat Objects, https://tc39.es/proposal-intl-duration-format/#durationformat-objects
+DurationFormat::DurationFormat(Object& prototype)
+    : Object(prototype)
+{
+}
+
+DurationFormat::Style DurationFormat::style_from_string(StringView style)
+{
+    if (style == "long"sv)
+        return Style::Long;
+    if (style == "short"sv)
+        return Style::Short;
+    if (style == "narrow"sv)
+        return Style::Narrow;
+    if (style == "digital"sv)
+        return Style::Digital;
+    VERIFY_NOT_REACHED();
+}
+
+StringView DurationFormat::style_to_string(Style style)
+{
+    switch (style) {
+    case Style::Long:
+        return "long"sv;
+    case Style::Short:
+        return "short"sv;
+    case Style::Narrow:
+        return "narrow"sv;
+    case Style::Digital:
+        return "digital"sv;
+    default:
+        VERIFY_NOT_REACHED();
+    }
+}
+
+DurationFormat::ValueStyle DurationFormat::date_style_from_string(StringView date_style)
+{
+    if (date_style == "long"sv)
+        return ValueStyle::Long;
+    if (date_style == "short"sv)
+        return ValueStyle::Short;
+    if (date_style == "narrow"sv)
+        return ValueStyle::Narrow;
+    VERIFY_NOT_REACHED();
+}
+
+DurationFormat::ValueStyle DurationFormat::time_style_from_string(StringView time_style)
+{
+    if (time_style == "long"sv)
+        return ValueStyle::Long;
+    if (time_style == "short"sv)
+        return ValueStyle::Short;
+    if (time_style == "narrow"sv)
+        return ValueStyle::Narrow;
+    if (time_style == "numeric"sv)
+        return ValueStyle::Numeric;
+    if (time_style == "2-digit"sv)
+        return ValueStyle::TwoDigit;
+    VERIFY_NOT_REACHED();
+}
+
+DurationFormat::ValueStyle DurationFormat::sub_second_style_from_string(StringView sub_second_style)
+{
+    if (sub_second_style == "long"sv)
+        return ValueStyle::Long;
+    if (sub_second_style == "short"sv)
+        return ValueStyle::Short;
+    if (sub_second_style == "narrow"sv)
+        return ValueStyle::Narrow;
+    if (sub_second_style == "numeric"sv)
+        return ValueStyle::Numeric;
+    VERIFY_NOT_REACHED();
+}
+
+DurationFormat::Display DurationFormat::display_from_string(StringView display)
+{
+    if (display == "auto"sv)
+        return Display::Auto;
+    if (display == "always"sv)
+        return Display::Always;
+    VERIFY_NOT_REACHED();
+}
+
+StringView DurationFormat::value_style_to_string(ValueStyle value_style)
+{
+    switch (value_style) {
+    case ValueStyle::Long:
+        return "long"sv;
+    case ValueStyle::Short:
+        return "short"sv;
+    case ValueStyle::Narrow:
+        return "narrow"sv;
+    case ValueStyle::Numeric:
+        return "numeric"sv;
+    case ValueStyle::TwoDigit:
+        return "2-digit"sv;
+    default:
+        VERIFY_NOT_REACHED();
+    }
+}
+
+StringView DurationFormat::display_to_string(Display display)
+{
+    switch (display) {
+    case Display::Auto:
+        return "auto"sv;
+    case Display::Always:
+        return "always"sv;
+    default:
+        VERIFY_NOT_REACHED();
+    }
+}
+
+// 1.1.2 GetDurationUnitOptions ( unit, options, baseStyle, stylesList, digitalBase, prevStyle ), https://tc39.es/proposal-intl-duration-format/#sec-getdurationunitoptions
+ThrowCompletionOr<DurationUnitOptions> get_duration_unit_options(GlobalObject& global_object, String const& unit, Object const& options, StringView base_style, Span<StringView const> styles_list, StringView digital_base, Optional<String> const& previous_style)
+{
+    auto& vm = global_object.vm();
+
+    // 1. Let style be ? GetOption(options, unit, "string", stylesList, undefined).
+    auto style_value = TRY(get_option(global_object, options, unit, OptionType::String, styles_list, Empty {}));
+
+    // 2. Let displayDefault be "always".
+    auto display_default = "always"sv;
+
+    String style;
+
+    // 3. If style is undefined, then
+    if (style_value.is_undefined()) {
+        // a. Set displayDefault to "auto".
+        display_default = "auto"sv;
+
+        // b. If baseStyle is "digital", then
+        if (base_style == "digital"sv) {
+            // i. Set style to digitalBase.
+            style = digital_base;
+        }
+        // c. Else,
+        else {
+            // i. Set style to baseStyle.
+            style = base_style;
+        }
+    } else {
+        style = style_value.as_string().string();
+    }
+
+    // 4. Let displayField be the string-concatenation of unit and "Display".
+    auto display_field = String::formatted("{}Display", unit);
+
+    // 5. Let display be ? GetOption(options, displayField, "string", « "auto", "always" », displayDefault).
+    auto display = TRY(get_option(global_object, options, display_field, OptionType::String, { "auto"sv, "always"sv }, display_default));
+
+    // 6. If prevStyle is "numeric" or "2-digit", then
+    if (previous_style == "numeric"sv || previous_style == "2-digit"sv) {
+        // a. If style is not "numeric" or "2-digit", then
+        if (style != "numeric"sv && style != "2-digit"sv) {
+            // i. Throw a RangeError exception.
+            return vm.throw_completion<RangeError>(global_object, ErrorType::IntlNonNumericOr2DigitAfterNumericOr2Digit);
+        }
+        // b. Else if unit is "minutes" or "seconds", then
+        else if (unit == "minutes"sv || unit == "seconds"sv) {
+            // i. Set style to "2-digit".
+            style = "2-digit"sv;
+        }
+    }
+
+    // 7. Return the Record { [[Style]]: style, [[Display]]: display }.
+    return DurationUnitOptions { .style = move(style), .display = display.as_string().string() };
+}
+
+}

Userland/Libraries/LibJS/Runtime/Intl/DurationFormat.h

@@ -0,0 +1,194 @@
+/*
+ * Copyright (c) 2022, Idan Horowitz <idan.horowitz@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <AK/Array.h>
+#include <AK/String.h>
+#include <LibJS/Runtime/Object.h>
+
+namespace JS::Intl {
+
+class DurationFormat final : public Object {
+    JS_OBJECT(DurationFormat, Object);
+
+public:
+    enum class Style {
+        Long,
+        Short,
+        Narrow,
+        Digital
+    };
+
+    enum class ValueStyle {
+        Long,
+        Short,
+        Narrow,
+        Numeric,
+        TwoDigit
+    };
+
+    enum class Display {
+        Auto,
+        Always
+    };
+
+    static constexpr auto relevant_extension_keys()
+    {
+        // 1.3.3 Internal slots, https://tc39.es/proposal-intl-duration-format/#sec-Intl.DurationFormat-internal-slots
+        // The value of the [[RelevantExtensionKeys]] internal slot is « "nu" ».
+        return AK::Array { "nu"sv };
+    }
+
+    explicit DurationFormat(Object& prototype);
+    virtual ~DurationFormat() override = default;
+
+    void set_locale(String locale) { m_locale = move(locale); }
+    String const& locale() const { return m_locale; }
+
+    void set_data_locale(String data_locale) { m_data_locale = move(data_locale); }
+    String const& data_locale() const { return m_data_locale; }
+
+    void set_numbering_system(String numbering_system) { m_numbering_system = move(numbering_system); }
+    String const& numbering_system() const { return m_numbering_system; }
+
+    void set_style(StringView style) { m_style = style_from_string(style); }
+    String style_string() const { return style_to_string(m_style); }
+
+    void set_years_style(StringView years_style) { m_years_style = date_style_from_string(years_style); }
+    StringView years_style_string() const { return value_style_to_string(m_years_style); }
+
+    void set_years_display(StringView years_display) { m_years_display = display_from_string(years_display); }
+    StringView years_display_string() const { return display_to_string(m_years_display); }
+
+    void set_months_style(StringView months_style) { m_months_style = date_style_from_string(months_style); }
+    StringView months_style_string() const { return value_style_to_string(m_months_style); }
+
+    void set_months_display(StringView months_display) { m_months_display = display_from_string(months_display); }
+    StringView months_display_string() const { return display_to_string(m_months_display); }
+
+    void set_weeks_style(StringView weeks_style) { m_weeks_style = date_style_from_string(weeks_style); }
+    StringView weeks_style_string() const { return value_style_to_string(m_weeks_style); }
+
+    void set_weeks_display(StringView weeks_display) { m_weeks_display = display_from_string(weeks_display); }
+    StringView weeks_display_string() const { return display_to_string(m_weeks_display); }
+
+    void set_days_style(StringView days_style) { m_days_style = date_style_from_string(days_style); }
+    StringView days_style_string() const { return value_style_to_string(m_days_style); }
+
+    void set_days_display(StringView days_display) { m_days_display = display_from_string(days_display); }
+    StringView days_display_string() const { return display_to_string(m_days_display); }
+
+    void set_hours_style(StringView hours_style) { m_hours_style = time_style_from_string(hours_style); }
+    StringView hours_style_string() const { return value_style_to_string(m_hours_style); }
+
+    void set_hours_display(StringView hours_display) { m_hours_display = display_from_string(hours_display); }
+    StringView hours_display_string() const { return display_to_string(m_hours_display); }
+
+    void set_minutes_style(StringView minutes_style) { m_minutes_style = time_style_from_string(minutes_style); }
+    StringView minutes_style_string() const { return value_style_to_string(m_minutes_style); }
+
+    void set_minutes_display(StringView minutes_display) { m_minutes_display = display_from_string(minutes_display); }
+    StringView minutes_display_string() const { return display_to_string(m_minutes_display); }
+
+    void set_seconds_style(StringView seconds_style) { m_seconds_style = time_style_from_string(seconds_style); }
+    StringView seconds_style_string() const { return value_style_to_string(m_seconds_style); }
+
+    void set_seconds_display(StringView seconds_display) { m_seconds_display = display_from_string(seconds_display); }
+    StringView seconds_display_string() const { return display_to_string(m_seconds_display); }
+
+    void set_milliseconds_style(StringView milliseconds_style) { m_milliseconds_style = sub_second_style_from_string(milliseconds_style); }
+    StringView milliseconds_style_string() const { return value_style_to_string(m_milliseconds_style); }
+
+    void set_milliseconds_display(StringView milliseconds_display) { m_milliseconds_display = display_from_string(milliseconds_display); }
+    StringView milliseconds_display_string() const { return display_to_string(m_milliseconds_display); }
+
+    void set_microseconds_style(StringView microseconds_style) { m_microseconds_style = sub_second_style_from_string(microseconds_style); }
+    StringView microseconds_style_string() const { return value_style_to_string(m_microseconds_style); }
+
+    void set_microseconds_display(StringView microseconds_display) { m_microseconds_display = display_from_string(microseconds_display); }
+    StringView microseconds_display_string() const { return display_to_string(m_microseconds_display); }
+
+    void set_nanoseconds_style(StringView nanoseconds_style) { m_nanoseconds_style = sub_second_style_from_string(nanoseconds_style); }
+    StringView nanoseconds_style_string() const { return value_style_to_string(m_nanoseconds_style); }
+
+    void set_nanoseconds_display(StringView nanoseconds_display) { m_nanoseconds_display = display_from_string(nanoseconds_display); }
+    StringView nanoseconds_display_string() const { return display_to_string(m_nanoseconds_display); }
+
+    void set_fractional_digits(Optional<u8> fractional_digits) { m_fractional_digits = move(fractional_digits); }
+    bool has_fractional_digits() const { return m_fractional_digits.has_value(); }
+    u8 fractional_digits() const { return m_fractional_digits.value(); }
+
+private:
+    static Style style_from_string(StringView style);
+    static StringView style_to_string(Style);
+    static ValueStyle date_style_from_string(StringView date_style);
+    static ValueStyle time_style_from_string(StringView time_style);
+    static ValueStyle sub_second_style_from_string(StringView sub_second_style);
+    static StringView value_style_to_string(ValueStyle);
+    static Display display_from_string(StringView display);
+    static StringView display_to_string(Display);
+
+    String m_locale;                                      // [[Locale]]
+    String m_data_locale;                                 // [[DataLocale]]
+    String m_numbering_system;                            // [[NumberingSystem]]
+    Style m_style;                                        // [[Style]]
+    ValueStyle m_years_style { ValueStyle::Long };        // [[YearsStyle]]
+    Display m_years_display { Display::Auto };            // [[YearsDisplay]]
+    ValueStyle m_months_style { ValueStyle::Long };       // [[MonthsStyle]]
+    Display m_months_display { Display::Auto };           // [[MonthsDisplay]]
+    ValueStyle m_weeks_style { ValueStyle::Long };        // [[WeeksStyle]]
+    Display m_weeks_display { Display::Auto };            // [[WeeksDisplay]]
+    ValueStyle m_days_style { ValueStyle::Long };         // [[DaysStyle]]
+    Display m_days_display { Display::Auto };             // [[DaysDisplay]]
+    ValueStyle m_hours_style { ValueStyle::Long };        // [[HoursStyle]]
+    Display m_hours_display { Display::Auto };            // [[HoursDisplay]]
+    ValueStyle m_minutes_style { ValueStyle::Long };      // [[MinutesStyle]]
+    Display m_minutes_display { Display::Auto };          // [[MinutesDisplay]]
+    ValueStyle m_seconds_style { ValueStyle::Long };      // [[SecondsStyle]]
+    Display m_seconds_display { Display::Auto };          // [[SecondsDisplay]]
+    ValueStyle m_milliseconds_style { ValueStyle::Long }; // [[MillisecondsStyle]]
+    Display m_milliseconds_display { Display::Auto };     // [[MillisecondsDisplay]]
+    ValueStyle m_microseconds_style { ValueStyle::Long }; // [[MicrosecondsStyle]]
+    Display m_microseconds_display { Display::Auto };     // [[MicrosecondsDisplay]]
+    ValueStyle m_nanoseconds_style { ValueStyle::Long };  // [[NanosecondsStyle]]
+    Display m_nanoseconds_display { Display::Auto };      // [[NanosecondsDisplay]]
+    Optional<u8> m_fractional_digits;                     // [[FractionalDigits]]
+};
+
+struct DurationInstanceComponent {
+    void (DurationFormat::*set_style_slot)(StringView);
+    void (DurationFormat::*set_display_slot)(StringView);
+    StringView unit;
+    Span<StringView const> values;
+    StringView digital_default;
+};
+
+// Table 1: Components of Duration Instances, https://tc39.es/proposal-intl-duration-format/#table-duration-component
+static constexpr AK::Array<StringView, 3> date_values = { "long"sv, "short"sv, "narrow"sv };
+static constexpr AK::Array<StringView, 5> time_values = { "long"sv, "short"sv, "narrow"sv, "numeric"sv, "2-digit"sv };
+static constexpr AK::Array<StringView, 4> sub_second_values = { "long"sv, "short"sv, "narrow"sv, "numeric"sv };
+static constexpr AK::Array<DurationInstanceComponent, 10> duration_instances_components {
+    DurationInstanceComponent { &DurationFormat::set_years_style, &DurationFormat::set_years_display, "years"sv, date_values, "narrow"sv },
+    DurationInstanceComponent { &DurationFormat::set_months_style, &DurationFormat::set_months_display, "months"sv, date_values, "narrow"sv },
+    DurationInstanceComponent { &DurationFormat::set_weeks_style, &DurationFormat::set_weeks_display, "weeks"sv, date_values, "narrow"sv },
+    DurationInstanceComponent { &DurationFormat::set_days_style, &DurationFormat::set_days_display, "days"sv, date_values, "narrow"sv },
+    DurationInstanceComponent { &DurationFormat::set_hours_style, &DurationFormat::set_hours_display, "hours"sv, time_values, "numeric"sv },
+    DurationInstanceComponent { &DurationFormat::set_minutes_style, &DurationFormat::set_minutes_display, "minutes"sv, time_values, "numeric"sv },
+    DurationInstanceComponent { &DurationFormat::set_seconds_style, &DurationFormat::set_seconds_display, "seconds"sv, time_values, "numeric"sv },
+    DurationInstanceComponent { &DurationFormat::set_milliseconds_style, &DurationFormat::set_milliseconds_display, "milliseconds"sv, sub_second_values, "numeric"sv },
+    DurationInstanceComponent { &DurationFormat::set_microseconds_style, &DurationFormat::set_microseconds_display, "microseconds"sv, sub_second_values, "numeric"sv },
+    DurationInstanceComponent { &DurationFormat::set_nanoseconds_style, &DurationFormat::set_nanoseconds_display, "nanoseconds"sv, sub_second_values, "numeric"sv },
+};
+
+struct DurationUnitOptions {
+    String style;
+    String display;
+};
+
+ThrowCompletionOr<DurationUnitOptions> get_duration_unit_options(GlobalObject& global_object, String const& unit, Object const& options, StringView base_style, Span<StringView const> styles_list, StringView digital_base, Optional<String> const& previous_style);
+
+}

Userland/Libraries/LibJS/Runtime/Intl/DurationFormatConstructor.cpp

@@ -0,0 +1,140 @@
+/*
+ * Copyright (c) 2022, Idan Horowitz <idan.horowitz@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <LibJS/Runtime/AbstractOperations.h>
+#include <LibJS/Runtime/GlobalObject.h>
+#include <LibJS/Runtime/Intl/AbstractOperations.h>
+#include <LibJS/Runtime/Intl/DurationFormat.h>
+#include <LibJS/Runtime/Intl/DurationFormatConstructor.h>
+
+namespace JS::Intl {
+
+// 1.2 The Intl.DurationFormat Constructor, https://tc39.es/proposal-intl-duration-format/#sec-intl-durationformat-constructor
+DurationFormatConstructor::DurationFormatConstructor(GlobalObject& global_object)
+    : NativeFunction(vm().names.DurationFormat.as_string(), *global_object.function_prototype())
+{
+}
+
+void DurationFormatConstructor::initialize(GlobalObject& global_object)
+{
+    NativeFunction::initialize(global_object);
+
+    auto& vm = this->vm();
+
+    // 1.3.1 Intl.DurationFormat.prototype, https://tc39.es/proposal-intl-duration-format/#sec-Intl.DurationFormat.prototype
+    define_direct_property(vm.names.prototype, global_object.intl_duration_format_prototype(), 0);
+    define_direct_property(vm.names.length, Value(0), Attribute::Configurable);
+}
+
+// 1.2.1 Intl.DurationFormat ( [ locales [ , options ] ] ), https://tc39.es/proposal-intl-duration-format/#sec-Intl.DurationFormat
+ThrowCompletionOr<Value> DurationFormatConstructor::call()
+{
+    // 1. If NewTarget is undefined, throw a TypeError exception.
+    return vm().throw_completion<TypeError>(global_object(), ErrorType::ConstructorWithoutNew, "Intl.DurationFormat");
+}
+
+// 1.2.1 Intl.DurationFormat ( [ locales [ , options ] ] ), https://tc39.es/proposal-intl-duration-format/#sec-Intl.DurationFormat
+ThrowCompletionOr<Object*> DurationFormatConstructor::construct(FunctionObject& new_target)
+{
+    auto& vm = this->vm();
+    auto& global_object = this->global_object();
+
+    auto locales = vm.argument(0);
+    auto options_value = vm.argument(1);
+
+    // 2. Let durationFormat be ? OrdinaryCreateFromConstructor(NewTarget, "%DurationFormatPrototype%", « [[InitializedDurationFormat]], [[Locale]], [[DataLocale]], [[NumberingSystem]], [[Style]], [[YearsStyle]], [[YearsDisplay]], [[MonthsStyle]], [[MonthsDisplay]] , [[WeeksStyle]], [[WeeksDisplay]] , [[DaysStyle]], [[DaysDisplay]] , [[HoursStyle]], [[HoursDisplay]] , [[MinutesStyle]], [[MinutesDisplay]] , [[SecondsStyle]], [[SecondsDisplay]] , [[MillisecondsStyle]], [[MillisecondsDisplay]] , [[MicrosecondsStyle]], [[MicrosecondsDisplay]] , [[NanosecondsStyle]], [[NanosecondsDisplay]], [[FractionalDigits]] »).
+    auto* duration_format = TRY(ordinary_create_from_constructor<DurationFormat>(global_object, new_target, &GlobalObject::intl_duration_format_prototype));
+
+    // 3. Let requestedLocales be ? CanonicalizeLocaleList(locales).
+    auto requested_locales = TRY(canonicalize_locale_list(global_object, locales));
+
+    // 4. Let options be ? GetOptionsObject(options).
+    auto* options = TRY(Temporal::get_options_object(global_object, options_value));
+
+    // 5. Let matcher be ? GetOption(options, "localeMatcher", "string", « "lookup", "best fit" », "best fit").
+    auto matcher = TRY(get_option(global_object, *options, vm.names.localeMatcher, OptionType::String, { "lookup"sv, "best fit"sv }, "best fit"sv));
+
+    // 6. Let numberingSystem be ? GetOption(options, "numberingSystem", "string", undefined, undefined).
+    auto numbering_system = TRY(get_option(global_object, *options, vm.names.numberingSystem, OptionType::String, {}, Empty {}));
+
+    // FIXME: Missing spec step - If numberingSystem is not undefined, then
+    if (!numbering_system.is_undefined()) {
+        // 7. If numberingSystem does not match the Unicode Locale Identifier type nonterminal, throw a RangeError exception.
+        if (numbering_system.is_undefined() || !Unicode::is_type_identifier(numbering_system.as_string().string()))
+            return vm.throw_completion<RangeError>(global_object, ErrorType::OptionIsNotValidValue, numbering_system, "numberingSystem"sv);
+    }
+
+    // 8. Let opt be the Record { [[localeMatcher]]: matcher, [[nu]]: numberingSystem }.
+    LocaleOptions opt {};
+    opt.locale_matcher = matcher;
+    opt.nu = numbering_system.is_undefined() ? Optional<String>() : numbering_system.as_string().string();
+
+    // 9. Let r be ResolveLocale(%DurationFormat%.[[AvailableLocales]], requestedLocales, opt, %DurationFormat%.[[RelevantExtensionKeys]], %DurationFormat%.[[LocaleData]]).
+    auto result = resolve_locale(requested_locales, opt, DurationFormat::relevant_extension_keys());
+
+    // 10. Let locale be r.[[locale]].
+    auto locale = move(result.locale);
+
+    // 11. Set durationFormat.[[Locale]] to locale.
+    duration_format->set_locale(move(locale));
+
+    // 12. Set durationFormat.[[NumberingSystem]] to r.[[nu]].
+    if (result.nu.has_value())
+        duration_format->set_numbering_system(result.nu.release_value());
+
+    // 13. Let style be ? GetOption(options, "style", "string", « "long", "short", "narrow", "digital" », "long").
+    auto style = TRY(get_option(global_object, *options, vm.names.style, OptionType::String, { "long"sv, "short"sv, "narrow"sv, "digital"sv }, "long"sv));
+
+    // 14. Set durationFormat.[[Style]] to style.
+    duration_format->set_style(style.as_string().string());
+
+    // 15. Set durationFormat.[[DataLocale]] to r.[[dataLocale]].
+    duration_format->set_data_locale(move(result.data_locale));
+
+    // 16. Let prevStyle be undefined.
+    Optional<String> previous_style;
+
+    // 17. For each row in Table 1, except the header row, in table order, do
+    for (auto const& duration_instances_component : duration_instances_components) {
+        // a. Let styleSlot be the Style Slot value.
+        auto style_slot = duration_instances_component.set_style_slot;
+
+        // b. Let displaySlot be the Display Slot value.
+        auto display_slot = duration_instances_component.set_display_slot;
+
+        // c. Let unit be the Unit value.
+        auto unit = duration_instances_component.unit;
+
+        // d. Let valueList be the Values value.
+        auto value_list = duration_instances_component.values;
+
+        // e. Let digitalBase be the Digital Default value.
+        auto digital_base = duration_instances_component.digital_default;
+
+        // f. Let unitOptions be ? GetDurationUnitOptions(unit, options, style, valueList, digitalBase, prevStyle).
+        auto unit_options = TRY(get_duration_unit_options(global_object, unit, *options, style.as_string().string(), value_list, digital_base, previous_style));
+
+        // g. Set the value of the styleSlot slot of durationFormat to unitOptions.[[Style]].
+        (duration_format->*style_slot)(unit_options.style);
+
+        // h. Set the value of the displaySlot slot of durationFormat to unitOptions.[[Display]].
+        (duration_format->*display_slot)(unit_options.display);
+
+        // i. If unit is one of "hours", "minutes", "seconds", "milliseconds", or "microseconds", then
+        if (unit.is_one_of("hours"sv, "minutes"sv, "seconds"sv, "milliseconds"sv, "microseconds"sv)) {
+            // i. Set prevStyle to unitOptions.[[Style]].
+            previous_style = unit_options.style;
+        }
+    }
+
+    // 18. Set durationFormat.[[FractionalDigits]] to ? GetNumberOption(options, "fractionalDigits", 0, 9, undefined).
+    duration_format->set_fractional_digits(Optional<u8>(TRY(get_number_option(global_object, *options, vm.names.fractionalDigits, 0, 9, {}))));
+
+    // 19. Return durationFormat.
+    return duration_format;
+}
+
+}

Userland/Libraries/LibJS/Runtime/Intl/DurationFormatConstructor.h

@@ -0,0 +1,28 @@
+/*
+ * Copyright (c) 2022, Idan Horowitz <idan.horowitz@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <LibJS/Runtime/NativeFunction.h>
+
+namespace JS::Intl {
+
+class DurationFormatConstructor final : public NativeFunction {
+    JS_OBJECT(DurationFormatConstructor, NativeFunction);
+
+public:
+    explicit DurationFormatConstructor(GlobalObject&);
+    virtual void initialize(GlobalObject&) override;
+    virtual ~DurationFormatConstructor() override = default;
+
+    virtual ThrowCompletionOr<Value> call() override;
+    virtual ThrowCompletionOr<Object*> construct(FunctionObject& new_target) override;
+
+private:
+    virtual bool has_constructor() const override { return true; }
+};
+
+}

Userland/Libraries/LibJS/Runtime/Intl/DurationFormatPrototype.cpp

@@ -0,0 +1,28 @@
+/*
+ * Copyright (c) 2022, Idan Horowitz <idan.horowitz@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <LibJS/Runtime/GlobalObject.h>
+#include <LibJS/Runtime/Intl/DurationFormatPrototype.h>
+
+namespace JS::Intl {
+
+// 1.4 Properties of the Intl.DurationFormat Prototype Object, https://tc39.es/proposal-intl-duration-format/#sec-properties-of-intl-durationformat-prototype-object
+DurationFormatPrototype::DurationFormatPrototype(GlobalObject& global_object)
+    : PrototypeObject(*global_object.object_prototype())
+{
+}
+
+void DurationFormatPrototype::initialize(GlobalObject& global_object)
+{
+    Object::initialize(global_object);
+
+    auto& vm = this->vm();
+
+    // 1.4.2 Intl.DurationFormat.prototype [ @@toStringTag ], https://tc39.es/proposal-intl-duration-format/#sec-Intl.DurationFormat.prototype-@@tostringtag
+    define_direct_property(*vm.well_known_symbol_to_string_tag(), js_string(vm, "Intl.DurationFormat"), Attribute::Configurable);
+}
+
+}

Userland/Libraries/LibJS/Runtime/Intl/DurationFormatPrototype.h

@@ -0,0 +1,23 @@
+/*
+ * Copyright (c) 2022, Idan Horowitz <idan.horowitz@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <LibJS/Runtime/Intl/DurationFormat.h>
+#include <LibJS/Runtime/PrototypeObject.h>
+
+namespace JS::Intl {
+
+class DurationFormatPrototype final : public PrototypeObject<DurationFormatPrototype, DurationFormat> {
+    JS_PROTOTYPE_OBJECT(DurationFormatPrototype, DurationFormat, Intl.DurationFormat);
+
+public:
+    explicit DurationFormatPrototype(GlobalObject&);
+    virtual void initialize(GlobalObject&) override;
+    virtual ~DurationFormatPrototype() override = default;
+};
+
+}

Userland/Libraries/LibJS/Runtime/Intl/Intl.cpp

@@ -11,6 +11,7 @@
 #include <LibJS/Runtime/Intl/CollatorConstructor.h>
 #include <LibJS/Runtime/Intl/DateTimeFormatConstructor.h>
 #include <LibJS/Runtime/Intl/DisplayNamesConstructor.h>
+#include <LibJS/Runtime/Intl/DurationFormatConstructor.h>
 #include <LibJS/Runtime/Intl/Intl.h>
 #include <LibJS/Runtime/Intl/ListFormatConstructor.h>
 #include <LibJS/Runtime/Intl/LocaleConstructor.h>
@@ -45,6 +46,7 @@ void Intl::initialize(GlobalObject& global_object)
     define_direct_property(vm.names.Collator, global_object.intl_collator_constructor(), attr);
     define_direct_property(vm.names.DateTimeFormat, global_object.intl_date_time_format_constructor(), attr);
     define_direct_property(vm.names.DisplayNames, global_object.intl_display_names_constructor(), attr);
+    define_direct_property(vm.names.DurationFormat, global_object.intl_duration_format_constructor(), attr);
     define_direct_property(vm.names.ListFormat, global_object.intl_list_format_constructor(), attr);
     define_direct_property(vm.names.Locale, global_object.intl_locale_constructor(), attr);
     define_direct_property(vm.names.NumberFormat, global_object.intl_number_format_constructor(), attr);