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Merged
lahma merged 2 commits into from
Jan 24, 2026
Merged

Add Intl.DateTimeFormat and update toLocaleString #2259

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c1cb72d
Add Intl.DateTimeFormat and update toLocaleString
lahma Jan 24, 2026
16366ec
fix test
lahma Jan 24, 2026
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7 changes: 4 additions & 3 deletions Jint.Tests/Runtime/EngineTests.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -1850,9 +1850,10 @@ public void DateToStringMethodsShouldUseCurrentTimeZoneAndCulture()
equal('Mon Jun 01 2015 05:00:00 GMT-0700 (Pacific Standard Time)', d.toString());
equal('Mon Jun 01 2015', d.toDateString());
equal('05:00:00 GMT-0700 (Pacific Standard Time)', d.toTimeString());
equal('lundi 1 juin 2015 05:00:00', d.toLocaleString());
equal('lundi 1 juin 2015', d.toLocaleDateString());
equal('05:00:00', d.toLocaleTimeString());
// ECMA-402 compliant: numeric defaults used when no options specified
equal('1/6/2015 5:00:00', d.toLocaleString());
equal('1/6/2015', d.toLocaleDateString());
equal('5:00:00', d.toLocaleTimeString());
");
}

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7 changes: 6 additions & 1 deletion Jint/Native/Array/ArrayPrototype.cs
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Expand Up @@ -1330,6 +1330,11 @@ private JsValue ToLocaleString(JsValue thisObject, JsCallArguments arguments)
return JsString.Empty;
}

// Per ECMA-402, always pass locales and options to element's toLocaleString
var locales = arguments.At(0);
var options = arguments.At(1);
var invokeArgs = new[] { locales, options };

using var r = new ValueStringBuilder();
for (uint k = 0; k < len; k++)
{
Expand All @@ -1339,7 +1344,7 @@ private JsValue ToLocaleString(JsValue thisObject, JsCallArguments arguments)
}
if (array.TryGetValue(k, out var nextElement) && !nextElement.IsNullOrUndefined())
{
var s = TypeConverter.ToString(Invoke(nextElement, "toLocaleString", []));
var s = TypeConverter.ToString(Invoke(nextElement, "toLocaleString", invokeArgs));
r.Append(s);
}
}
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146 changes: 143 additions & 3 deletions Jint/Native/Date/DatePrototype.cs
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Expand Up @@ -3,6 +3,7 @@
using System.Globalization;
using System.Runtime.CompilerServices;
using System.Runtime.InteropServices;
using Jint.Native.Intl;
using Jint.Native.Object;
using Jint.Native.Symbol;
using Jint.Runtime;
Expand Down Expand Up @@ -211,6 +212,7 @@ private JsValue ToTimeString(JsValue thisObject, JsCallArguments arguments)

/// <summary>
/// https://tc39.es/ecma262/#sec-date.prototype.tolocalestring
/// https://tc39.es/ecma402/#sup-date.prototype.tolocalestring
/// </summary>
private JsValue ToLocaleString(JsValue thisObject, JsCallArguments arguments)
{
Expand All @@ -221,11 +223,37 @@ private JsValue ToLocaleString(JsValue thisObject, JsCallArguments arguments)
return "Invalid Date";
}

return ToLocalTime(dateInstance).ToString("F", Engine.Options.Culture);
var locales = arguments.At(0);
var options = arguments.At(1);

// Per ECMA-402 ToDateTimeOptions("any", "all"):
// If no date/time options are specified, use default numeric components
var optionsObj = IntlUtilities.CoerceOptionsToObject(Engine, options);
var needDefaults = NeedDateTimeDefaults(optionsObj, checkDate: true, checkTime: true);

if (needDefaults)
{
// Add default date and time components per spec
// Use null prototype per ToDateTimeOptions step 2: ObjectCreate(options)
var newOptions = ObjectInstance.OrdinaryObjectCreate(Engine, null);
CopyOptions(optionsObj, newOptions);
newOptions.Set("year", "numeric");
newOptions.Set("month", "numeric");
newOptions.Set("day", "numeric");
newOptions.Set("hour", "numeric");
newOptions.Set("minute", "numeric");
newOptions.Set("second", "numeric");
options = newOptions;
}

// Use Intl.DateTimeFormat for locale-aware formatting
var dateTimeFormat = (JsDateTimeFormat) Engine.Realm.Intrinsics.DateTimeFormat.Construct([locales, options], Engine.Realm.Intrinsics.DateTimeFormat);
return dateTimeFormat.Format(ToLocalTime(dateInstance));
}

/// <summary>
/// https://tc39.es/ecma262/#sec-date.prototype.tolocaledatestring
/// https://tc39.es/ecma402/#sup-date.prototype.tolocaledatestring
/// </summary>
private JsValue ToLocaleDateString(JsValue thisObject, JsCallArguments arguments)
{
Expand All @@ -236,11 +264,34 @@ private JsValue ToLocaleDateString(JsValue thisObject, JsCallArguments arguments
return "Invalid Date";
}

return ToLocalTime(dateInstance).ToString("D", Engine.Options.Culture);
var locales = arguments.At(0);
var options = arguments.At(1);

// Per ECMA-402 ToDateTimeOptions("date", "date"):
// If no date options are specified, use default numeric date components
var optionsObj = IntlUtilities.CoerceOptionsToObject(Engine, options);
var needDefaults = NeedDateTimeDefaults(optionsObj, checkDate: true, checkTime: false);

if (needDefaults)
{
// Add default date components per spec
// Use null prototype per ToDateTimeOptions step 2: ObjectCreate(options)
var newOptions = ObjectInstance.OrdinaryObjectCreate(Engine, null);
CopyOptions(optionsObj, newOptions);
newOptions.Set("year", "numeric");
newOptions.Set("month", "numeric");
newOptions.Set("day", "numeric");
options = newOptions;
}

// Use Intl.DateTimeFormat for locale-aware formatting
var dateTimeFormat = (JsDateTimeFormat) Engine.Realm.Intrinsics.DateTimeFormat.Construct([locales, options], Engine.Realm.Intrinsics.DateTimeFormat);
return dateTimeFormat.Format(ToLocalTime(dateInstance));
}

/// <summary>
/// https://tc39.es/ecma262/#sec-date.prototype.tolocaletimestring
/// https://tc39.es/ecma402/#sup-date.prototype.tolocaletimestring
/// </summary>
private JsValue ToLocaleTimeString(JsValue thisObject, JsCallArguments arguments)
{
Expand All @@ -251,7 +302,96 @@ private JsValue ToLocaleTimeString(JsValue thisObject, JsCallArguments arguments
return "Invalid Date";
}

return ToLocalTime(dateInstance).ToString("T", Engine.Options.Culture);
var locales = arguments.At(0);
var options = arguments.At(1);

// Per ECMA-402 ToDateTimeOptions("time", "time"):
// If no time options are specified, use default numeric time components
var optionsObj = IntlUtilities.CoerceOptionsToObject(Engine, options);
var needDefaults = NeedDateTimeDefaults(optionsObj, checkDate: false, checkTime: true);

if (needDefaults)
{
// Add default time components per spec
// Use null prototype per ToDateTimeOptions step 2: ObjectCreate(options)
var newOptions = ObjectInstance.OrdinaryObjectCreate(Engine, null);
CopyOptions(optionsObj, newOptions);
newOptions.Set("hour", "numeric");
newOptions.Set("minute", "numeric");
newOptions.Set("second", "numeric");
options = newOptions;
}

// Use Intl.DateTimeFormat for locale-aware formatting
var dateTimeFormat = (JsDateTimeFormat) Engine.Realm.Intrinsics.DateTimeFormat.Construct([locales, options], Engine.Realm.Intrinsics.DateTimeFormat);
return dateTimeFormat.Format(ToLocalTime(dateInstance));
}

/// <summary>
/// Checks if default date/time options should be applied per ECMA-402 ToDateTimeOptions.
/// Returns true if no relevant options are specified and dateStyle/timeStyle are not present.
/// </summary>
private static bool NeedDateTimeDefaults(ObjectInstance options, bool checkDate, bool checkTime)
{
// If dateStyle or timeStyle is present, don't add defaults
if (!options.Get("dateStyle").IsUndefined() || !options.Get("timeStyle").IsUndefined())
{
return false;
}

// Check date-related properties
if (checkDate)
{
if (!options.Get("weekday").IsUndefined() ||
!options.Get("year").IsUndefined() ||
!options.Get("month").IsUndefined() ||
!options.Get("day").IsUndefined() ||
!options.Get("era").IsUndefined())
{
return false;
}
}

// Check time-related properties
if (checkTime)
{
if (!options.Get("dayPeriod").IsUndefined() ||
!options.Get("hour").IsUndefined() ||
!options.Get("minute").IsUndefined() ||
!options.Get("second").IsUndefined() ||
!options.Get("fractionalSecondDigits").IsUndefined())
{
return false;
}
}

return true;
}

/// <summary>
/// Copies all defined options from source to target, preserving user-specified values.
/// </summary>
private static void CopyOptions(ObjectInstance source, ObjectInstance target)
{
// Copy all options that should be preserved (general + date/time components)
var optionsToCopy = new[]
{
// General options
"localeMatcher", "formatMatcher", "calendar", "numberingSystem", "timeZone", "hourCycle", "hour12",
"dateStyle", "timeStyle",
// Date components
"weekday", "era", "year", "month", "day",
// Time components
"dayPeriod", "hour", "minute", "second", "fractionalSecondDigits"
};
foreach (var option in optionsToCopy)
{
var value = source.Get(option);
if (!value.IsUndefined())
{
target.Set(option, value);
}
}
}

private JsValue GetTime(JsValue thisObject, JsCallArguments arguments)
Expand Down
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