LibJS: Implement the Intl.NumberFormat constructor

Author: https://github.com/trflynn89
Commit: https://github.com/SerenityOS/serenity/commit/e42ba7f7481
Pull-request: https://github.com/SerenityOS/serenity/pull/9945
Reviewed-by: https://github.com/linusg ✅

Userland/Libraries/LibJS/Runtime/CommonPropertyNames.h

@@ -96,6 +96,7 @@ namespace JS {
     P(clz32)                                 \
     P(codePointAt)                           \
     P(collation)                             \
+    P(compactDisplay)                        \
     P(compareExchange)                       \
     P(compile)                               \
     P(concat)                                \
@@ -110,6 +111,9 @@ namespace JS {
     P(count)                                 \
     P(countReset)                            \
     P(create)                                \
+    P(currency)                              \
+    P(currencyDisplay)                       \
+    P(currencySign)                          \
     P(dateAdd)                               \
     P(dateFromFields)                        \
     P(day)                                   \
@@ -293,6 +297,11 @@ namespace JS {
     P(milliseconds)                          \
     P(min)                                   \
     P(minimize)                              \
+    P(maximumFractionDigits)                 \
+    P(maximumSignificantDigits)              \
+    P(minimumFractionDigits)                 \
+    P(minimumIntegerDigits)                  \
+    P(minimumSignificantDigits)              \
     P(minute)                                \
     P(minutes)                               \
     P(month)                                 \
@@ -306,6 +315,7 @@ namespace JS {
     P(nanoseconds)                           \
     P(negated)                               \
     P(next)                                  \
+    P(notation)                              \
     P(now)                                   \
     P(numberingSystem)                       \
     P(numeric)                               \
@@ -382,6 +392,7 @@ namespace JS {
     P(setYear)                               \
     P(shift)                                 \
     P(sign)                                  \
+    P(signDisplay)                           \
     P(sin)                                   \
     P(since)                                 \
     P(sinh)                                  \
@@ -448,9 +459,12 @@ namespace JS {
     P(undefined)                             \
     P(unescape)                              \
     P(unicode)                               \
+    P(unit)                                  \
+    P(unitDisplay)                           \
     P(until)                                 \
     P(unregister)                            \
     P(unshift)                               \
+    P(useGrouping)                           \
     P(value)                                 \
     P(valueOf)                               \
     P(values)                                \

Userland/Libraries/LibJS/Runtime/ErrorTypes.h

@@ -32,6 +32,9 @@
     M(InOperatorWithObject, "'in' operator must be used on an object")                                                                  \
     M(InstanceOfOperatorBadPrototype, "'prototype' property of {} is not an object")                                                    \
     M(IntlInvalidLanguageTag, "{} is not a structurally valid language tag")                                                            \
+    M(IntlMinimumExceedsMaximum, "Minimum value {} is larger than maximum value {}")                                                    \
+    M(IntlNumberIsNaNOrOutOfRange, "Value {} is NaN or is not between {} and {}")                                                       \
+    M(IntlOptionUndefined, "Option {} must be defined when option {} is {}")                                                            \
     M(InvalidAssignToConst, "Invalid assignment to const variable")                                                                     \
     M(InvalidCodePoint, "Invalid code point {}, must be an integer no less than 0 and no greater than 0x10FFFF")                        \
     M(InvalidFormat, "Invalid {} format")                                                                                               \

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

@@ -6,7 +6,9 @@
 
 #include <AK/AllOf.h>
 #include <AK/AnyOf.h>
+#include <AK/Array.h>
 #include <AK/CharacterTypes.h>
+#include <AK/Find.h>
 #include <AK/Function.h>
 #include <AK/QuickSort.h>
 #include <AK/TypeCasts.h>
@@ -121,7 +123,7 @@ String canonicalize_unicode_locale_id(Unicode::LocaleID& locale)
 }
 
 // 6.3.1 IsWellFormedCurrencyCode ( currency ), https://tc39.es/ecma402/#sec-canonicalcodefordisplaynames
-static bool is_well_formed_currency_code(StringView currency)
+bool is_well_formed_currency_code(StringView currency)
 {
     // 1. Let normalized be the result of mapping currency to upper case as described in 6.1.
     // 2. If the number of elements in normalized is not 3, return false.
@@ -136,6 +138,53 @@ static bool is_well_formed_currency_code(StringView currency)
     return true;
 }
 
+// 6.5.1 IsWellFormedUnitIdentifier ( unitIdentifier ), https://tc39.es/ecma402/#sec-iswellformedunitidentifier
+bool is_well_formed_unit_identifier(StringView unit_identifier)
+{
+    // 6.5.2 IsSanctionedSimpleUnitIdentifier ( unitIdentifier ), https://tc39.es/ecma402/#sec-iswellformedunitidentifier
+    constexpr auto is_sanctioned_simple_unit_identifier = [](StringView unit_identifier) {
+        // 1. If unitIdentifier is listed in Table 2 below, return true.
+        // 2. Else, return false.
+        static constexpr auto sanctioned_units = AK::Array { "acre"sv, "bit"sv, "byte"sv, "celsius"sv, "centimeter"sv, "day"sv, "degree"sv, "fahrenheit"sv, "fluid-ounce"sv, "foot"sv, "gallon"sv, "gigabit"sv, "gigabyte"sv, "gram"sv, "hectare"sv, "hour"sv, "inch"sv, "kilobit"sv, "kilobyte"sv, "kilogram"sv, "kilometer"sv, "liter"sv, "megabit"sv, "megabyte"sv, "meter"sv, "mile"sv, "mile-scandinavian"sv, "milliliter"sv, "millimeter"sv, "millisecond"sv, "minute"sv, "month"sv, "ounce"sv, "percent"sv, "petabyte"sv, "pound"sv, "second"sv, "stone"sv, "terabit"sv, "terabyte"sv, "week"sv, "yard"sv, "year"sv };
+        return find(sanctioned_units.begin(), sanctioned_units.end(), unit_identifier) != sanctioned_units.end();
+    };
+
+    // 1. If the result of IsSanctionedSimpleUnitIdentifier(unitIdentifier) is true, then
+    if (is_sanctioned_simple_unit_identifier(unit_identifier)) {
+        // a. Return true.
+        return true;
+    }
+
+    auto indices = unit_identifier.find_all("-per-"sv);
+
+    // 2. If the substring "-per-" does not occur exactly once in unitIdentifier, then
+    if (indices.size() != 1) {
+        // a. Return false.
+        return false;
+    }
+
+    // 3. Let numerator be the substring of unitIdentifier from the beginning to just before "-per-".
+    auto numerator = unit_identifier.substring_view(0, indices[0]);
+
+    // 4. If the result of IsSanctionedSimpleUnitIdentifier(numerator) is false, then
+    if (!is_sanctioned_simple_unit_identifier(numerator)) {
+        // a. Return false.
+        return false;
+    }
+
+    // 5. Let denominator be the substring of unitIdentifier from just after "-per-" to the end.
+    auto denominator = unit_identifier.substring_view(indices[0] + 5);
+
+    // 6. If the result of IsSanctionedSimpleUnitIdentifier(denominator) is false, then
+    if (!is_sanctioned_simple_unit_identifier(denominator)) {
+        // a. Return false.
+        return false;
+    }
+
+    // 7. Return true.
+    return true;
+}
+
 // 9.2.1 CanonicalizeLocaleList ( locales ), https://tc39.es/ecma402/#sec-canonicalizelocalelist
 Vector<String> canonicalize_locale_list(GlobalObject& global_object, Value locales)
 {
@@ -328,6 +377,9 @@ String insert_unicode_extension_and_canonicalize(Unicode::LocaleID locale, Unico
 template<typename T>
 static auto& find_key_in_value(T& value, StringView key)
 {
+    if (key == "nu"sv)
+        return value.nu;
+
     // If you hit this point, you must add any missing keys from [[RelevantExtensionKeys]] to LocaleOptions and LocaleResult.
     VERIFY_NOT_REACHED();
 }
@@ -615,6 +667,45 @@ Value get_option(GlobalObject& global_object, Value options, PropertyName const&
     return value;
 }
 
+// 9.2.14 DefaultNumberOption ( value, minimum, maximum, fallback ), https://tc39.es/ecma402/#sec-defaultnumberoption
+Optional<int> default_number_option(GlobalObject& global_object, Value value, int minimum, int maximum, Optional<int> fallback)
+{
+    auto& vm = global_object.vm();
+
+    // 1. If value is undefined, return fallback.
+    if (value.is_undefined())
+        return fallback;
+
+    // 2. Let value be ? ToNumber(value).
+    value = value.to_number(global_object);
+    if (vm.exception())
+        return {};
+
+    // 3. If value is NaN or less than minimum or greater than maximum, throw a RangeError exception.
+    if (value.is_nan() || (value.as_double() < minimum) || (value.as_double() > maximum)) {
+        vm.throw_exception<RangeError>(global_object, ErrorType::IntlNumberIsNaNOrOutOfRange, value, minimum, maximum);
+        return {};
+    }
+
+    // 4. Return floor(value).
+    return floor(value.as_double());
+}
+
+// 9.2.15 GetNumberOption ( options, property, minimum, maximum, fallback ), https://tc39.es/ecma402/#sec-getnumberoption
+Optional<int> get_number_option(GlobalObject& global_object, Object& options, PropertyName const& property, int minimum, int maximum, Optional<int> fallback)
+{
+    auto& vm = global_object.vm();
+
+    // 1. Assert: Type(options) is Object.
+    // 2. Let value be ? Get(options, property).
+    auto value = options.get(property);
+    if (vm.exception())
+        return {};
+
+    // 3. Return ? DefaultNumberOption(value, minimum, maximum, fallback).
+    return default_number_option(global_object, value, minimum, maximum, fallback);
+}
+
 // 9.2.16 PartitionPattern ( pattern ), https://tc39.es/ecma402/#sec-partitionpattern
 Vector<PatternPartition> partition_pattern(StringView pattern)
 {

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

@@ -20,11 +20,13 @@ using Fallback = Variant<Empty, bool, StringView>;
 
 struct LocaleOptions {
     Value locale_matcher;
+    Optional<String> nu;
 };
 
 struct LocaleResult {
     String locale;
     String data_locale;
+    Optional<String> nu;
 };
 
 struct PatternPartition {
@@ -33,6 +35,8 @@ struct PatternPartition {
 };
 
 Optional<Unicode::LocaleID> is_structurally_valid_language_tag(StringView locale);
+bool is_well_formed_currency_code(StringView currency);
+bool is_well_formed_unit_identifier(StringView unit_identifier);
 String canonicalize_unicode_locale_id(Unicode::LocaleID& locale);
 Vector<String> canonicalize_locale_list(GlobalObject&, Value locales);
 Optional<String> best_available_locale(StringView const& locale);
@@ -41,6 +45,8 @@ Vector<String> lookup_supported_locales(Vector<String> const& requested_locales)
 Array* supported_locales(GlobalObject&, Vector<String> const& requested_locales, Value options);
 Object* coerce_options_to_object(GlobalObject& global_object, Value options);
 Value get_option(GlobalObject& global_object, Value options, PropertyName const& property, Value::Type type, Vector<StringView> const& values, Fallback fallback);
+Optional<int> default_number_option(GlobalObject& global_object, Value value, int minimum, int maximum, Optional<int> fallback);
+Optional<int> get_number_option(GlobalObject& global_object, Object& options, PropertyName const& property, int minimum, int maximum, Optional<int> fallback);
 Vector<PatternPartition> partition_pattern(StringView pattern);
 String insert_unicode_extension_and_canonicalize(Unicode::LocaleID locale_id, Unicode::LocaleExtension extension);
 LocaleResult resolve_locale(Vector<String> const& requested_locales, LocaleOptions const& options, Vector<StringView> const& relevant_extension_keys);

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

@@ -6,11 +6,376 @@
 
 #include <LibJS/Runtime/AbstractOperations.h>
 #include <LibJS/Runtime/GlobalObject.h>
+#include <LibJS/Runtime/Intl/AbstractOperations.h>
 #include <LibJS/Runtime/Intl/NumberFormat.h>
 #include <LibJS/Runtime/Intl/NumberFormatConstructor.h>
+#include <LibUnicode/CurrencyCode.h>
+#include <LibUnicode/Locale.h>
 
 namespace JS::Intl {
 
+static Vector<StringView> const& number_format_relevant_extension_keys()
+{
+    // 15.3.3 Internal slots, https://tc39.es/ecma402/#sec-intl.numberformat-internal-slots
+    // The value of the [[RelevantExtensionKeys]] internal slot is « "nu" ».
+    static Vector<StringView> relevant_extension_keys { "nu"sv };
+    return relevant_extension_keys;
+}
+
+// 15.1.1 SetNumberFormatDigitOptions ( intlObj, options, mnfdDefault, mxfdDefault, notation ), https://tc39.es/ecma402/#sec-setnfdigitoptions
+static void set_number_format_digit_options(GlobalObject& global_object, NumberFormat& intl_object, Object& options, int default_min_fraction_digits, int default_max_fraction_digits, NumberFormat::Notation notation)
+{
+    auto& vm = global_object.vm();
+
+    // 1. Assert: Type(intlObj) is Object.
+    // 2. Assert: Type(options) is Object.
+    // 3. Assert: Type(mnfdDefault) is Number.
+    // 4. Assert: Type(mxfdDefault) is Number.
+
+    // 5. Let mnid be ? GetNumberOption(options, "minimumIntegerDigits,", 1, 21, 1).
+    auto min_integer_digits = get_number_option(global_object, options, vm.names.minimumIntegerDigits, 1, 21, 1);
+    if (vm.exception())
+        return;
+
+    // 6. Let mnfd be ? Get(options, "minimumFractionDigits").
+    auto min_fraction_digits = options.get(vm.names.minimumFractionDigits);
+    if (vm.exception())
+        return;
+
+    // 7. Let mxfd be ? Get(options, "maximumFractionDigits").
+    auto max_fraction_digits = options.get(vm.names.maximumFractionDigits);
+    if (vm.exception())
+        return;
+
+    // 8. Let mnsd be ? Get(options, "minimumSignificantDigits").
+    auto min_significant_digits = options.get(vm.names.minimumSignificantDigits);
+    if (vm.exception())
+        return;
+
+    // 9. Let mxsd be ? Get(options, "maximumSignificantDigits").
+    auto max_significant_digits = options.get(vm.names.maximumSignificantDigits);
+    if (vm.exception())
+        return;
+
+    // 10. Set intlObj.[[MinimumIntegerDigits]] to mnid.
+    intl_object.set_min_integer_digits(*min_integer_digits);
+
+    // 11. If mnsd is not undefined or mxsd is not undefined, then
+    if (!min_significant_digits.is_undefined() || !max_significant_digits.is_undefined()) {
+        // a. Set intlObj.[[RoundingType]] to significantDigits.
+        intl_object.set_rounding_type(NumberFormat::RoundingType::SignificantDigits);
+
+        // b. Let mnsd be ? DefaultNumberOption(mnsd, 1, 21, 1).
+        auto min_digits = default_number_option(global_object, min_significant_digits, 1, 21, 1);
+        if (vm.exception())
+            return;
+
+        // c. Let mxsd be ? DefaultNumberOption(mxsd, mnsd, 21, 21).
+        auto max_digits = default_number_option(global_object, max_significant_digits, *min_digits, 21, 21);
+        if (vm.exception())
+            return;
+
+        // d. Set intlObj.[[MinimumSignificantDigits]] to mnsd.
+        intl_object.set_min_significant_digits(*min_digits);
+
+        // e. Set intlObj.[[MaximumSignificantDigits]] to mxsd.
+        intl_object.set_max_significant_digits(*max_digits);
+    }
+    // 12. Else if mnfd is not undefined or mxfd is not undefined, then
+    else if (!min_fraction_digits.is_undefined() || !max_fraction_digits.is_undefined()) {
+        // a. Set intlObj.[[RoundingType]] to fractionDigits.
+        intl_object.set_rounding_type(NumberFormat::RoundingType::FractionDigits);
+
+        // b. Let mnfd be ? DefaultNumberOption(mnfd, 0, 20, undefined).
+        auto min_digits = default_number_option(global_object, min_fraction_digits, 0, 20, {});
+        if (vm.exception())
+            return;
+
+        // c. Let mxfd be ? DefaultNumberOption(mxfd, 0, 20, undefined).
+        auto max_digits = default_number_option(global_object, max_fraction_digits, 0, 20, {});
+        if (vm.exception())
+            return;
+
+        // d. If mnfd is undefined, set mnfd to min(mnfdDefault, mxfd).
+        if (!min_digits.has_value()) {
+            min_digits = min(default_min_fraction_digits, *max_digits);
+        }
+        // e. Else if mxfd is undefined, set mxfd to max(mxfdDefault, mnfd).
+        else if (!max_digits.has_value()) {
+            max_digits = max(default_max_fraction_digits, *min_digits);
+        }
+        // f. Else if mnfd is greater than mxfd, throw a RangeError exception.
+        else if (*min_digits > *max_digits) {
+            vm.throw_exception<RangeError>(global_object, ErrorType::IntlMinimumExceedsMaximum, *min_digits, *max_digits);
+            return;
+        }
+
+        // g. Set intlObj.[[MinimumFractionDigits]] to mnfd.
+        intl_object.set_min_fraction_digits(*min_digits);
+
+        // h. Set intlObj.[[MaximumFractionDigits]] to mxfd.
+        intl_object.set_max_fraction_digits(*max_digits);
+    }
+    // 13. Else if notation is "compact", then
+    else if (notation == NumberFormat::Notation::Compact) {
+        // a. Set intlObj.[[RoundingType]] to compactRounding.
+        intl_object.set_rounding_type(NumberFormat::RoundingType::CompactRounding);
+
+    }
+    // 14. Else,
+    else {
+        // a. Set intlObj.[[RoundingType]] to fractionDigits.
+        intl_object.set_rounding_type(NumberFormat::RoundingType::FractionDigits);
+
+        // b. Set intlObj.[[MinimumFractionDigits]] to mnfdDefault.
+        intl_object.set_min_fraction_digits(default_min_fraction_digits);
+
+        // c. Set intlObj.[[MaximumFractionDigits]] to mxfdDefault.
+        intl_object.set_max_fraction_digits(default_max_fraction_digits);
+    }
+}
+
+// 15.1.3 CurrencyDigits ( currency ), https://tc39.es/ecma402/#sec-currencydigits
+static int currency_digits(StringView currency)
+{
+    // 1. If the ISO 4217 currency and funds code list contains currency as an alphabetic code, return the minor
+    //    unit value corresponding to the currency from the list; otherwise, return 2.
+    if (auto currency_code = Unicode::get_currency_code(currency); currency_code.has_value())
+        return currency_code->minor_unit.value_or(2);
+    return 2;
+}
+
+// 15.1.13 SetNumberFormatUnitOptions ( intlObj, options ), https://tc39.es/ecma402/#sec-setnumberformatunitoptions
+static void set_number_format_unit_options(GlobalObject& global_object, NumberFormat& intl_object, Object& options)
+{
+    auto& vm = global_object.vm();
+
+    // 1. Assert: Type(intlObj) is Object.
+    // 2. Assert: Type(options) is Object.
+
+    // 3. Let style be ? GetOption(options, "style", "string", « "decimal", "percent", "currency", "unit" », "decimal").
+    auto style = get_option(global_object, &options, vm.names.style, Value::Type::String, { "decimal"sv, "percent"sv, "currency"sv, "unit"sv }, "decimal"sv);
+    if (vm.exception())
+        return;
+
+    // 4. Set intlObj.[[Style]] to style.
+    intl_object.set_style(style.as_string().string());
+
+    // 5. Let currency be ? GetOption(options, "currency", "string", undefined, undefined).
+    auto currency = get_option(global_object, &options, vm.names.currency, Value::Type::String, {}, Empty {});
+    if (vm.exception())
+        return;
+
+    // 6. If currency is undefined, then
+    if (currency.is_undefined()) {
+        // a. If style is "currency", throw a TypeError exception.
+        if (intl_object.style() == NumberFormat::Style::Currency) {
+            vm.throw_exception<TypeError>(global_object, ErrorType::IntlOptionUndefined, "currency"sv, "style"sv, style);
+            return;
+        }
+    }
+    // 7. Else,
+    //     a. If the result of IsWellFormedCurrencyCode(currency) is false, throw a RangeError exception.
+    else if (!is_well_formed_currency_code(currency.as_string().string())) {
+        vm.throw_exception<RangeError>(global_object, ErrorType::OptionIsNotValidValue, currency, "currency"sv);
+        return;
+    }
+
+    // 8. Let currencyDisplay be ? GetOption(options, "currencyDisplay", "string", « "code", "symbol", "narrowSymbol", "name" », "symbol").
+    auto currency_display = get_option(global_object, &options, vm.names.currencyDisplay, Value::Type::String, { "code"sv, "symbol"sv, "narrowSymbol"sv, "name"sv }, "symbol"sv);
+    if (vm.exception())
+        return;
+
+    // 9. Let currencySign be ? GetOption(options, "currencySign", "string", « "standard", "accounting" », "standard").
+    auto currency_sign = get_option(global_object, &options, vm.names.currencySign, Value::Type::String, { "standard"sv, "accounting"sv }, "standard"sv);
+    if (vm.exception())
+        return;
+
+    // 10. Let unit be ? GetOption(options, "unit", "string", undefined, undefined).
+    auto unit = get_option(global_object, &options, vm.names.unit, Value::Type::String, {}, Empty {});
+    if (vm.exception())
+        return;
+
+    // 11. If unit is undefined, then
+    if (unit.is_undefined()) {
+        // a. If style is "unit", throw a TypeError exception.
+        if (intl_object.style() == NumberFormat::Style::Unit) {
+            vm.throw_exception<TypeError>(global_object, ErrorType::IntlOptionUndefined, "unit"sv, "style"sv, style);
+            return;
+        }
+    }
+    // 12. Else,
+    //     a. If the result of IsWellFormedUnitIdentifier(unit) is false, throw a RangeError exception.
+    else if (!is_well_formed_unit_identifier(unit.as_string().string())) {
+        vm.throw_exception<RangeError>(global_object, ErrorType::OptionIsNotValidValue, unit, "unit"sv);
+        return;
+    }
+
+    // 13. Let unitDisplay be ? GetOption(options, "unitDisplay", "string", « "short", "narrow", "long" », "short").
+    auto unit_display = get_option(global_object, &options, vm.names.unitDisplay, Value::Type::String, { "short"sv, "narrow"sv, "long"sv }, "short"sv);
+    if (vm.exception())
+        return;
+
+    // 14. If style is "currency", then
+    if (intl_object.style() == NumberFormat::Style::Currency) {
+        // a. Let currency be the result of converting currency to upper case as specified in 6.1.
+        // b. Set intlObj.[[Currency]] to currency.
+        intl_object.set_currency(currency.as_string().string().to_uppercase());
+
+        // c. Set intlObj.[[CurrencyDisplay]] to currencyDisplay.
+        intl_object.set_currency_display(currency_display.as_string().string());
+
+        // d. Set intlObj.[[CurrencySign]] to currencySign.
+        intl_object.set_currency_sign(currency_sign.as_string().string());
+    }
+
+    // 15. If style is "unit", then
+    if (intl_object.style() == NumberFormat::Style::Unit) {
+        // a. Set intlObj.[[Unit]] to unit.
+        intl_object.set_unit(unit.as_string().string());
+
+        // b. Set intlObj.[[UnitDisplay]] to unitDisplay.
+        intl_object.set_unit_display(unit_display.as_string().string());
+    }
+}
+
+// 15.1.2 InitializeNumberFormat ( numberFormat, locales, options ), https://tc39.es/ecma402/#sec-initializenumberformat
+static NumberFormat* initialize_number_format(GlobalObject& global_object, NumberFormat& number_format, Value locales, Value options)
+{
+    auto& vm = global_object.vm();
+
+    // 1. Let requestedLocales be ? CanonicalizeLocaleList(locales).
+    auto requested_locales = canonicalize_locale_list(global_object, locales);
+    if (vm.exception())
+        return {};
+
+    // 2. Set options to ? CoerceOptionsToObject(options).
+    options = coerce_options_to_object(global_object, options);
+    if (vm.exception())
+        return {};
+
+    // 3. Let opt be a new Record.
+    LocaleOptions opt {};
+
+    // 4. Let matcher be ? GetOption(options, "localeMatcher", "string", « "lookup", "best fit" », "best fit").
+    auto matcher = get_option(global_object, options, vm.names.localeMatcher, Value::Type::String, { "lookup"sv, "best fit"sv }, "best fit"sv);
+    if (vm.exception())
+        return {};
+
+    // 5. Set opt.[[localeMatcher]] to matcher.
+    opt.locale_matcher = matcher;
+
+    // 6. Let numberingSystem be ? GetOption(options, "numberingSystem", "string", undefined, undefined).
+    auto numbering_system = get_option(global_object, options, vm.names.numberingSystem, Value::Type::String, {}, Empty {});
+    if (vm.exception())
+        return {};
+
+    // 7. If numberingSystem is not undefined, then
+    if (!numbering_system.is_undefined()) {
+        // a. If numberingSystem does not match the Unicode Locale Identifier type nonterminal, throw a RangeError exception.
+        if (!Unicode::is_type_identifier(numbering_system.as_string().string())) {
+            vm.throw_exception<RangeError>(global_object, ErrorType::OptionIsNotValidValue, numbering_system, "numberingSystem"sv);
+            return {};
+        }
+
+        // 8. Set opt.[[nu]] to numberingSystem.
+        opt.nu = numbering_system.as_string().string();
+    }
+
+    // 9. Let localeData be %NumberFormat%.[[LocaleData]].
+    // 10. Let r be ResolveLocale(%NumberFormat%.[[AvailableLocales]], requestedLocales, opt, %NumberFormat%.[[RelevantExtensionKeys]], localeData).
+    auto result = resolve_locale(requested_locales, opt, number_format_relevant_extension_keys());
+
+    // 11. Set numberFormat.[[Locale]] to r.[[locale]].
+    number_format.set_locale(move(result.locale));
+
+    // 12. Set numberFormat.[[DataLocale]] to r.[[dataLocale]].
+    number_format.set_data_locale(move(result.data_locale));
+
+    // 13. Set numberFormat.[[NumberingSystem]] to r.[[nu]].
+    number_format.set_numbering_system(result.nu.release_value());
+
+    // 14. Perform ? SetNumberFormatUnitOptions(numberFormat, options).
+    set_number_format_unit_options(global_object, number_format, options.as_object());
+    if (vm.exception())
+        return {};
+
+    // 15. Let style be numberFormat.[[Style]].
+    auto style = number_format.style();
+
+    int default_min_fraction_digits = 0;
+    int default_max_fraction_digits = 0;
+
+    // 16. If style is "currency", then
+    if (style == NumberFormat::Style::Currency) {
+        // a. Let currency be numberFormat.[[Currency]].
+        auto const& currency = number_format.currency();
+
+        // b. Let cDigits be CurrencyDigits(currency).
+        int digits = currency_digits(currency);
+
+        // c. Let mnfdDefault be cDigits.
+        default_min_fraction_digits = digits;
+
+        // d. Let mxfdDefault be cDigits.
+        default_max_fraction_digits = digits;
+    }
+    // 17. Else,
+    else {
+        // a. Let mnfdDefault be 0.
+        default_min_fraction_digits = 0;
+
+        // b. If style is "percent", then
+        //     i. Let mxfdDefault be 0.
+        // c. Else,
+        //     i. Let mxfdDefault be 3.
+        default_max_fraction_digits = style == NumberFormat::Style::Percent ? 0 : 3;
+    }
+
+    // 18. Let notation be ? GetOption(options, "notation", "string", « "standard", "scientific", "engineering", "compact" », "standard").
+    auto notation = get_option(global_object, options, vm.names.notation, Value::Type::String, { "standard"sv, "scientific"sv, "engineering"sv, "compact"sv }, "standard"sv);
+    if (vm.exception())
+        return {};
+
+    // 19. Set numberFormat.[[Notation]] to notation.
+    number_format.set_notation(notation.as_string().string());
+
+    // 20. Perform ? SetNumberFormatDigitOptions(numberFormat, options, mnfdDefault, mxfdDefault, notation).
+    set_number_format_digit_options(global_object, number_format, options.as_object(), default_min_fraction_digits, default_max_fraction_digits, number_format.notation());
+    if (vm.exception())
+        return {};
+
+    // 21. Let compactDisplay be ? GetOption(options, "compactDisplay", "string", « "short", "long" », "short").
+    auto compact_display = get_option(global_object, options, vm.names.compactDisplay, Value::Type::String, { "short"sv, "long"sv }, "short"sv);
+    if (vm.exception())
+        return {};
+
+    // 22. If notation is "compact", then
+    if (number_format.notation() == NumberFormat::Notation::Compact) {
+        // a. Set numberFormat.[[CompactDisplay]] to compactDisplay.
+        number_format.set_compact_display(compact_display.as_string().string());
+    }
+
+    // 23. Let useGrouping be ? GetOption(options, "useGrouping", "boolean", undefined, true).
+    auto use_grouping = get_option(global_object, options, vm.names.useGrouping, Value::Type::Boolean, {}, true);
+    if (vm.exception())
+        return {};
+
+    // 24. Set numberFormat.[[UseGrouping]] to useGrouping.
+    number_format.set_use_grouping(use_grouping.as_bool());
+
+    // 25. Let signDisplay be ? GetOption(options, "signDisplay", "string", « "auto", "never", "always", "exceptZero" », "auto").
+    auto sign_display = get_option(global_object, options, vm.names.signDisplay, Value::Type::String, { "auto"sv, "never"sv, "always"sv, "exceptZero"sv }, "auto"sv);
+    if (vm.exception())
+        return {};
+
+    // 26. Set numberFormat.[[SignDisplay]] to signDisplay.
+    number_format.set_sign_display(sign_display.as_string().string());
+
+    // 27. Return numberFormat.
+    return &number_format;
+}
+
 // 15.2 The Intl.NumberFormat Constructor, https://tc39.es/ecma402/#sec-intl-numberformat-constructor
 NumberFormatConstructor::NumberFormatConstructor(GlobalObject& global_object)
     : NativeFunction(vm().names.NumberFormat.as_string(), *global_object.function_prototype())
@@ -41,11 +406,23 @@ Value NumberFormatConstructor::construct(FunctionObject& new_target)
     auto& vm = this->vm();
     auto& global_object = this->global_object();
 
+    auto locales = vm.argument(0);
+    auto options = vm.argument(1);
+
     // 2. Let numberFormat be ? OrdinaryCreateFromConstructor(newTarget, "%NumberFormat.prototype%", « [[InitializedNumberFormat]], [[Locale]], [[DataLocale]], [[NumberingSystem]], [[Style]], [[Unit]], [[UnitDisplay]], [[Currency]], [[CurrencyDisplay]], [[CurrencySign]], [[MinimumIntegerDigits]], [[MinimumFractionDigits]], [[MaximumFractionDigits]], [[MinimumSignificantDigits]], [[MaximumSignificantDigits]], [[RoundingType]], [[Notation]], [[CompactDisplay]], [[UseGrouping]], [[SignDisplay]], [[BoundFormat]] »).
     auto* number_format = ordinary_create_from_constructor<NumberFormat>(global_object, new_target, &GlobalObject::intl_number_format_prototype);
     if (vm.exception())
         return {};
 
+    // 3. Perform ? InitializeNumberFormat(numberFormat, locales, options).
+    initialize_number_format(global_object, *number_format, locales, options);
+    if (vm.exception())
+        return {};
+
+    // 4. If the implementation supports the normative optional constructor mode of 4.3 Note 1, then
+    //     a. Let this be the this value.
+    //     b. Return ? ChainNumberFormat(numberFormat, NewTarget, this).
+
     // 5. Return numberFormat.
     return number_format;
 }

Userland/Libraries/LibJS/Tests/builtins/Intl/NumberFormat/NumberFormat.js

@@ -1,5 +1,353 @@
+describe("errors", () => {
+    test("structurally invalid tag", () => {
+        expect(() => {
+            new Intl.NumberFormat("root");
+        }).toThrowWithMessage(RangeError, "root is not a structurally valid language tag");
+
+        expect(() => {
+            new Intl.NumberFormat("en-");
+        }).toThrowWithMessage(RangeError, "en- is not a structurally valid language tag");
+
+        expect(() => {
+            new Intl.NumberFormat("Latn");
+        }).toThrowWithMessage(RangeError, "Latn is not a structurally valid language tag");
+
+        expect(() => {
+            new Intl.NumberFormat("en-u-aa-U-aa");
+        }).toThrowWithMessage(RangeError, "en-u-aa-U-aa is not a structurally valid language tag");
+    });
+
+    test("options is an invalid type", () => {
+        expect(() => {
+            new Intl.NumberFormat("en", null);
+        }).toThrowWithMessage(TypeError, "ToObject on null or undefined");
+    });
+
+    test("localeMatcher option is invalid ", () => {
+        expect(() => {
+            new Intl.NumberFormat("en", { localeMatcher: "hello!" });
+        }).toThrowWithMessage(RangeError, "hello! is not a valid value for option localeMatcher");
+    });
+
+    test("numberingSystem option is invalid ", () => {
+        expect(() => {
+            new Intl.NumberFormat("en", { numberingSystem: "hello!" });
+        }).toThrowWithMessage(RangeError, "hello! is not a valid value for option numberingSystem");
+    });
+
+    test("style option is invalid ", () => {
+        expect(() => {
+            new Intl.NumberFormat("en", { style: "hello!" });
+        }).toThrowWithMessage(RangeError, "hello! is not a valid value for option style");
+    });
+
+    test("currency option is undefined when required ", () => {
+        expect(() => {
+            new Intl.NumberFormat("en", { style: "currency" });
+        }).toThrowWithMessage(
+            TypeError,
+            "Option currency must be defined when option style is currency"
+        );
+    });
+
+    test("currency option is invalid ", () => {
+        expect(() => {
+            new Intl.NumberFormat("en", { currency: "hello!" });
+        }).toThrowWithMessage(RangeError, "hello! is not a valid value for option currency");
+    });
+
+    test("currencyDisplay option is invalid ", () => {
+        expect(() => {
+            new Intl.NumberFormat("en", { currencyDisplay: "hello!" });
+        }).toThrowWithMessage(RangeError, "hello! is not a valid value for option currencyDisplay");
+    });
+
+    test("currencySign option is invalid ", () => {
+        expect(() => {
+            new Intl.NumberFormat("en", { currencySign: "hello!" });
+        }).toThrowWithMessage(RangeError, "hello! is not a valid value for option currencySign");
+    });
+
+    test("unit option is undefined when required ", () => {
+        expect(() => {
+            new Intl.NumberFormat("en", { style: "unit" });
+        }).toThrowWithMessage(TypeError, "Option unit must be defined when option style is unit");
+    });
+
+    test("unit option is invalid ", () => {
+        expect(() => {
+            new Intl.NumberFormat("en", { unit: "hello!" });
+        }).toThrowWithMessage(RangeError, "hello! is not a valid value for option unit");
+
+        expect(() => {
+            new Intl.NumberFormat("en", { unit: "acre-bit" });
+        }).toThrowWithMessage(RangeError, "acre-bit is not a valid value for option unit");
+
+        expect(() => {
+            new Intl.NumberFormat("en", { unit: "acre-per-bit-per-byte" });
+        }).toThrowWithMessage(
+            RangeError,
+            "acre-per-bit-per-byte is not a valid value for option unit"
+        );
+    });
+
+    test("unitDisplay option is invalid ", () => {
+        expect(() => {
+            new Intl.NumberFormat("en", { unitDisplay: "hello!" });
+        }).toThrowWithMessage(RangeError, "hello! is not a valid value for option unitDisplay");
+    });
+
+    test("notation option is invalid ", () => {
+        expect(() => {
+            new Intl.NumberFormat("en", { notation: "hello!" });
+        }).toThrowWithMessage(RangeError, "hello! is not a valid value for option notation");
+    });
+
+    test("minimumIntegerDigits option is invalid ", () => {
+        expect(() => {
+            new Intl.NumberFormat("en", { minimumIntegerDigits: 1n });
+        }).toThrowWithMessage(TypeError, "Cannot convert BigInt to number");
+
+        expect(() => {
+            new Intl.NumberFormat("en", { minimumIntegerDigits: "hello!" });
+        }).toThrowWithMessage(RangeError, "Value NaN is NaN or is not between 1 and 21");
+
+        expect(() => {
+            new Intl.NumberFormat("en", { minimumIntegerDigits: 0 });
+        }).toThrowWithMessage(RangeError, "Value 0 is NaN or is not between 1 and 21");
+
+        expect(() => {
+            new Intl.NumberFormat("en", { minimumIntegerDigits: 22 });
+        }).toThrowWithMessage(RangeError, "Value 22 is NaN or is not between 1 and 21");
+    });
+
+    test("minimumFractionDigits option is invalid ", () => {
+        expect(() => {
+            new Intl.NumberFormat("en", { minimumFractionDigits: 1n });
+        }).toThrowWithMessage(TypeError, "Cannot convert BigInt to number");
+
+        expect(() => {
+            new Intl.NumberFormat("en", { minimumFractionDigits: "hello!" });
+        }).toThrowWithMessage(RangeError, "Value NaN is NaN or is not between 0 and 20");
+
+        expect(() => {
+            new Intl.NumberFormat("en", { minimumFractionDigits: -1 });
+        }).toThrowWithMessage(RangeError, "Value -1 is NaN or is not between 0 and 20");
+
+        expect(() => {
+            new Intl.NumberFormat("en", { minimumFractionDigits: 21 });
+        }).toThrowWithMessage(RangeError, "Value 21 is NaN or is not between 0 and 20");
+    });
+
+    test("maximumFractionDigits option is invalid ", () => {
+        expect(() => {
+            new Intl.NumberFormat("en", { maximumFractionDigits: 1n });
+        }).toThrowWithMessage(TypeError, "Cannot convert BigInt to number");
+
+        expect(() => {
+            new Intl.NumberFormat("en", { maximumFractionDigits: "hello!" });
+        }).toThrowWithMessage(RangeError, "Value NaN is NaN or is not between 0 and 20");
+
+        expect(() => {
+            new Intl.NumberFormat("en", { maximumFractionDigits: -1 });
+        }).toThrowWithMessage(RangeError, "Value -1 is NaN or is not between 0 and 20");
+
+        expect(() => {
+            new Intl.NumberFormat("en", { maximumFractionDigits: 21 });
+        }).toThrowWithMessage(RangeError, "Value 21 is NaN or is not between 0 and 20");
+
+        expect(() => {
+            new Intl.NumberFormat("en", { minimumFractionDigits: 10, maximumFractionDigits: 5 });
+        }).toThrowWithMessage(RangeError, "Minimum value 10 is larger than maximum value 5");
+    });
+
+    test("minimumSignificantDigits option is invalid ", () => {
+        expect(() => {
+            new Intl.NumberFormat("en", { minimumSignificantDigits: 1n });
+        }).toThrowWithMessage(TypeError, "Cannot convert BigInt to number");
+
+        expect(() => {
+            new Intl.NumberFormat("en", { minimumSignificantDigits: "hello!" });
+        }).toThrowWithMessage(RangeError, "Value NaN is NaN or is not between 1 and 21");
+
+        expect(() => {
+            new Intl.NumberFormat("en", { minimumSignificantDigits: 0 });
+        }).toThrowWithMessage(RangeError, "Value 0 is NaN or is not between 1 and 21");
+
+        expect(() => {
+            new Intl.NumberFormat("en", { minimumSignificantDigits: 22 });
+        }).toThrowWithMessage(RangeError, "Value 22 is NaN or is not between 1 and 21");
+    });
+
+    test("maximumSignificantDigits option is invalid ", () => {
+        expect(() => {
+            new Intl.NumberFormat("en", { maximumSignificantDigits: 1n });
+        }).toThrowWithMessage(TypeError, "Cannot convert BigInt to number");
+
+        expect(() => {
+            new Intl.NumberFormat("en", { maximumSignificantDigits: "hello!" });
+        }).toThrowWithMessage(RangeError, "Value NaN is NaN or is not between 1 and 21");
+
+        expect(() => {
+            new Intl.NumberFormat("en", { maximumSignificantDigits: 0 });
+        }).toThrowWithMessage(RangeError, "Value 0 is NaN or is not between 1 and 21");
+
+        expect(() => {
+            new Intl.NumberFormat("en", { maximumSignificantDigits: 22 });
+        }).toThrowWithMessage(RangeError, "Value 22 is NaN or is not between 1 and 21");
+    });
+
+    test("compactDisplay option is invalid ", () => {
+        expect(() => {
+            new Intl.NumberFormat("en", { compactDisplay: "hello!" });
+        }).toThrowWithMessage(RangeError, "hello! is not a valid value for option compactDisplay");
+    });
+
+    test("signDisplay option is invalid ", () => {
+        expect(() => {
+            new Intl.NumberFormat("en", { signDisplay: "hello!" });
+        }).toThrowWithMessage(RangeError, "hello! is not a valid value for option signDisplay");
+    });
+});
+
 describe("normal behavior", () => {
     test("length is 0", () => {
         expect(Intl.NumberFormat).toHaveLength(0);
     });
+
+    test("all valid localeMatcher options", () => {
+        ["lookup", "best fit"].forEach(localeMatcher => {
+            expect(() => {
+                new Intl.NumberFormat("en", { localeMatcher: localeMatcher });
+            }).not.toThrow();
+        });
+    });
+
+    test("valid numberingSystem options", () => {
+        ["latn", "arab", "abc-def-ghi"].forEach(numberingSystem => {
+            expect(() => {
+                new Intl.NumberFormat("en", { numberingSystem: numberingSystem });
+            }).not.toThrow();
+        });
+    });
+
+    test("all valid style options", () => {
+        ["decimal", "percent"].forEach(style => {
+            expect(() => {
+                new Intl.NumberFormat("en", { style: style });
+            }).not.toThrow();
+        });
+
+        expect(() => {
+            new Intl.NumberFormat("en", { style: "currency", currency: "USD" });
+        }).not.toThrow();
+
+        expect(() => {
+            new Intl.NumberFormat("en", { style: "unit", unit: "degree" });
+        }).not.toThrow();
+    });
+
+    test("valid currency options", () => {
+        ["USD", "EUR", "XAG"].forEach(currency => {
+            expect(() => {
+                new Intl.NumberFormat("en", { currency: currency });
+            }).not.toThrow();
+        });
+    });
+
+    test("all valid currencyDisplay options", () => {
+        ["code", "symbol", "narrowSymbol", "name"].forEach(currencyDisplay => {
+            expect(() => {
+                new Intl.NumberFormat("en", { currencyDisplay: currencyDisplay });
+            }).not.toThrow();
+        });
+    });
+
+    test("all valid currencySign options", () => {
+        ["standard", "accounting"].forEach(currencySign => {
+            expect(() => {
+                new Intl.NumberFormat("en", { currencySign: currencySign });
+            }).not.toThrow();
+        });
+    });
+
+    test("valid unit options", () => {
+        ["acre", "acre-per-bit"].forEach(unit => {
+            expect(() => {
+                new Intl.NumberFormat("en", { unit: unit });
+            }).not.toThrow();
+        });
+    });
+
+    test("all valid unitDisplay options", () => {
+        ["short", "narrow", "long"].forEach(unitDisplay => {
+            expect(() => {
+                new Intl.NumberFormat("en", { unitDisplay: unitDisplay });
+            }).not.toThrow();
+        });
+    });
+
+    test("all valid notation options", () => {
+        ["standard", "scientific", "engineering", "compact"].forEach(notation => {
+            expect(() => {
+                new Intl.NumberFormat("en", { notation: notation });
+            }).not.toThrow();
+        });
+    });
+
+    test("all valid minimumIntegerDigits options", () => {
+        for (let i = 1; i <= 21; ++i) {
+            expect(() => {
+                new Intl.NumberFormat("en", { minimumIntegerDigits: i });
+            }).not.toThrow();
+        }
+    });
+
+    test("all valid minimumFractionDigits options", () => {
+        for (let i = 0; i <= 20; ++i) {
+            expect(() => {
+                new Intl.NumberFormat("en", { minimumFractionDigits: i });
+            }).not.toThrow();
+        }
+    });
+
+    test("all valid maximumFractionDigits options", () => {
+        for (let i = 0; i <= 20; ++i) {
+            expect(() => {
+                new Intl.NumberFormat("en", { maximumFractionDigits: i });
+            }).not.toThrow();
+        }
+    });
+
+    test("all valid minimumSignificantDigits options", () => {
+        for (let i = 1; i <= 21; ++i) {
+            expect(() => {
+                new Intl.NumberFormat("en", { minimumSignificantDigits: i });
+            }).not.toThrow();
+        }
+    });
+
+    test("all valid maximumSignificantDigits options", () => {
+        for (let i = 1; i <= 21; ++i) {
+            expect(() => {
+                new Intl.NumberFormat("en", { maximumSignificantDigits: i });
+            }).not.toThrow();
+        }
+    });
+
+    test("all valid compactDisplay options", () => {
+        ["short", "long"].forEach(compactDisplay => {
+            expect(() => {
+                new Intl.NumberFormat("en", { compactDisplay: compactDisplay });
+            }).not.toThrow();
+        });
+    });
+
+    test("all valid signDisplay options", () => {
+        ["auto", "never", "always", "exceptZero"].forEach(signDisplay => {
+            expect(() => {
+                new Intl.NumberFormat("en", { signDisplay: signDisplay });
+            }).not.toThrow();
+        });
+    });
 });