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Intl.DateTimeFormat

Learn localization with Intl.DateTimeFormat.

Intl.DateTimeFormat

To display a date to users, Intl.DateTimeFormat localizes it. It takes a locale code and options; it formats output according to that locale.

Example: new Intl.DateTimeFormat("tr-TR", { day: "numeric", month: "long", year: "numeric" }). You format with .format(date). tr-TR is Turkish for Turkey; en-US American English; de-DE German. month: "long" gives the full month name (March); month: "short" the abbreviation (Mar); month: "numeric" the number (3). For timezone add timeZone: "UTC"; the output then does not depend on the machine's timezone. This is the standard way to display dates in multilingual apps.

Locale codes

A locale code has the language-region form: tr-TR, en-US, en-GB, de-DE, fr-FR, ja-JP. The same language uses different formats in different regions: en-US uses month/day/year order, en-GB day/month/year.

Example: new Intl.DateTimeFormat("en-US").format(new Date("2024-03-15")) gives 3/15/2024; for en-GB it is 15/03/2024. Without a locale Node.js uses the machine default, which makes tests fragile. Always pass an explicit locale in tests. With month: "long" the month name comes in the locale's language: "Mart" in tr-TR, "March" in en-US. In this lesson's exercise we will use the tr-TR locale together with the UTC timezone.

Practice Print a date in a localized format

Define const date = new Date("2024-03-15T00:00:00Z");. Create a formatter with const fmt = new Intl.DateTimeFormat("tr-TR", { day: "numeric", month: "long", year: "numeric", timeZone: "UTC" });. Print with console.log(fmt.format(date)).

Starter code

index.js
// Define a UTC date
// write here

// Create a tr-TR formatter
// write here

// Print the formatted date
// write here

Sample solution

index.js
const date = new Date("2024-03-15T00:00:00Z");
const fmt = new Intl.DateTimeFormat("tr-TR", { day: "numeric", month: "long", year: "numeric", timeZone: "UTC" });
console.log(fmt.format(date));

Expected output

15 Mart 2024

Questions and answers

Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.

1 Match each option to its output

Term Meaning
day: numeric Day number
month: long Full month name
year: numeric Year number
timeZone: UTC UTC timezone

2 What month name does Intl.DateTimeFormat("tr-TR", { month: "long" }) give?

index.js
new Intl.DateTimeFormat("tr-TR", { month: "long" }).format(new Date("2024-03-15"))
  • March
  • Mar
  • 3
  • Mart Correct answer

Explanation: In the tr-TR locale March is written as 'Mart'.

3 Complete the DateTimeFormat call

Question 
const fmt = new Intl.____("tr-TR", { day: "numeric", month: "long", year: "numeric", timeZone: "UTC" });
Answer 
const fmt = new Intl.DateTimeFormat("tr-TR", { day: "numeric", month: "long", year: "numeric", timeZone: "UTC" });

Explanation: Intl.DateTimeFormat creates a localized formatter.

All lessons in Intermediate

1 Events

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  2. on and emit
  3. once
  4. removeListener
  5. error event
  6. Summary - Events

2 Streams

  1. What are streams?
  2. Readable stream
  3. Writable stream
  4. pipe
  5. Transform stream
  6. Summary - Streams

3 HTTP server

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  2. Request and response
  3. Routing
  4. JSON response
  5. Query string
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4 Project: Helper library

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  3. Number helpers
  4. Date helpers
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  3. app.get
  4. app.post
  5. app.listen
  6. Summary - Express basics

6 Middleware

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16 Debugging

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