Modern JavaScript and a project · Lesson 43 of 45

Dates and localised formatting

Date, and showing dates, numbers and money in Arabic and English.

7 minutes2 games

new Date() gives the current time; new Date(2026, 0, 15) builds a date (months start at 0: January is 0!). To display dates nicely in any language, use Intl.

JavaScript

const exam = new Date(2026, 11, 20, 10, 30)
console.log(exam.getFullYear(), exam.getMonth() + 1, exam.getDate())

const opts = { weekday: "long", day: "numeric", month: "long", year: "numeric" }
console.log(new Intl.DateTimeFormat("en-US", opts).format(exam))
console.log(new Intl.DateTimeFormat("ar-EG", opts).format(exam))

const days = Math.ceil((exam - new Date(2026, 10, 30)) / (1000 * 60 * 60 * 24))
console.log(days, "days to go")

console.log(new Intl.NumberFormat("ar-EG", { style: "currency", currency: "EGP" }).format(1499.5))
console.log(new Intl.NumberFormat("en-US").format(1234567.891))

What's the output?

const d = new Date(2026, 0, 31)
console.log(d.getMonth())

What will this code print?

Exercise

Print the number of days between 1 and 31 March 2026 in UTC (30) so daylight-saving changes do not alter the result.

Expected output: 30

JavaScript

const start = new Date(Date.UTC(2026, 2, 1))
const end = new Date(Date.UTC(2026, 2, 31))

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JavaScript

Modern JavaScript and a project · Lesson 43 of 45

Dates and localised formatting

Date, and showing dates, numbers and money in Arabic and English.

7 minutes2 games

new Date() gives the current time; new Date(2026, 0, 15) builds a date (months start at 0: January is 0!). To display dates nicely in any language, use Intl.

JavaScript

const exam = new Date(2026, 11, 20, 10, 30)
console.log(exam.getFullYear(), exam.getMonth() + 1, exam.getDate())

const opts = { weekday: "long", day: "numeric", month: "long", year: "numeric" }
console.log(new Intl.DateTimeFormat("en-US", opts).format(exam))
console.log(new Intl.DateTimeFormat("ar-EG", opts).format(exam))

const days = Math.ceil((exam - new Date(2026, 10, 30)) / (1000 * 60 * 60 * 24))
console.log(days, "days to go")

console.log(new Intl.NumberFormat("ar-EG", { style: "currency", currency: "EGP" }).format(1499.5))
console.log(new Intl.NumberFormat("en-US").format(1234567.891))

What's the output?

const d = new Date(2026, 0, 31)
console.log(d.getMonth())

What will this code print?

Exercise

Print the number of days between 1 and 31 March 2026 in UTC (30) so daylight-saving changes do not alter the result.

Expected output: 30

JavaScript

const start = new Date(Date.UTC(2026, 2, 1))
const end = new Date(Date.UTC(2026, 2, 31))

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