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Date ​

Times are represented in native JavaScript with the Date object.

For things not covered by the native Date, see date-fns.

Syntax ​

js
new Date()
new Date(dateString)
new Date(dateObject)

new Date(year, monthIndex)
new Date(year, monthIndex, day, ...)

Example:

js
// Will get the system's current date/time as UTC
const now = new Date();

// Can pass in specific values to make a specific date
// Months are 0-indexed
const birthday = new Date(1999, 8, 15);

Dates can be constructed with specific times as well.

Date parsing ​

Sometimes you'll be given a value, and need to convert that into a Date object. Unfortunately, outside of the Date time string format this is not guaranteed support at all.

This means that you'll often be required to parse your own string, into a date.

Timezones ​

Timezones are a bastard, and always have been in JavaScript.

For dealing with them, you could go down the native Intl route (if supported) or the library route.

Some libraries include:

You can specify custom behaviour for printing out Date objects using the Intl.DateTimeFormat builtin.

Example:

js
const now = new Date();

const local = new Intl.DateTimeFormat('en-GB', { 
	timeZone: 'Australia/Melbourne',
	dateStyle: 'full',
	timeStyle: 'long'
});

// 'Thursday, 20 July 2023 at 13:41:16 GMT+10'
local.format(date);

Get current browser timezone ​

To get the current browser Timezone, use the Intl builtin resolvedOptions().

js
// Australia/Melbourne
const timezone = Intl.DateTimeFormat().resolvedOptions().timeZone;

Temporal ​

Temporal is a proposed new namespace to be added into ECMAScript, which hopes to fix the glaring issues with the Date prototype.

Moment.js ​

Moment.js was previously the go-to standard library for using dates in JavaScript.

It has since been thoroughly deprecated, to the point where Moment.js themselves recommend abandoning the project.

For modern date libraries: