JavaScript Date Format Tester

Summary

JavaScript Date Format Tester lets you interactively explore the browser-native Intl.DateTimeFormat API without writing code. Choose any BCP 47 locale, set the weekday, year, month, day, hour, minute, and second display styles, then see the formatted result for the current moment and six diverse sample dates — including edge cases like New Year, leap day, and end of year. The generated code snippet is ready to paste into your project.

How it works

1. Select a locale from the dropdown (e.g. en-US, de-DE, ja-JP) or type a custom BCP 47 tag.
2. Toggle the date and time component options — weekday, year, month, day, hour, minute, second.
3. Choose a display style (long, short, narrow, numeric, 2-digit) for each active option.
4. The formatted output updates live for the current date and six sample dates.
5. Copy the generated Intl.DateTimeFormat code snippet with one click.

Use cases

• Preview how a date looks for users in different regions before shipping.
• Find the right combination of options for a localized UI date display.
• Debug unexpected date formatting behavior in your JavaScript app.
• Generate the exact Intl.DateTimeFormat constructor call to paste into code.
• Quickly preview how numeric vs. long month styles render for any selected locale.
• Test edge-case dates like leap day, New Year, and year-end formatting.

Frequently Asked Questions