A Moment.js tutorial

Moment.js is a JavaScript library that helps you manage dates, in the browser and in Node.js. The current release line is Moment.js 2.

One thing to know before you start: the Moment team calls it a legacy project in maintenance mode. They still publish bug fixes, but no new features. If you already have Moment in a project, there’s no urgent reason to rip it out. For a new project I would look at Day.js (1.x, with an API very close to Moment’s), Luxon (3.x, from the same team) or the built-in Temporal API. Temporal is also one of the 10 browser APIs that replaced a library I used to install.

This article explains the basics and the most common usages of Moment, for when you still need it.

Installation

You can include it directly in your page using a script tag, from unpkg.com:

<script src="https://unpkg.com/moment" />

or using npm:

npm install moment

If you install using npm you need to import the package (using ES Modules):

import moment from 'moment'

or require it (using CommonJS):

const moment = require('moment')

Get the current date and time

const date = moment()

Parse a date

A moment object can be initialized with a date by passing it a string:

const date = moment(string)

it accepts any string, parsed according to (in order):

• ISO 8601
• The RFC 2822 Date Time format
• the formats accepted by the Date object

ISO 8601 is definitely the most convenient. Here’s a format reference:

Set a date

Format a date

When you want to output the content of a plain JavaScript Date object, you have little options to determine the formatting. All you can do is to use the built-in methods, and compose the date as you want using them.

Moment offers a handy way to format the date according to your needs, using the format() method:

date.format(string)

The string format accepts the same formats I described in the “Parse a date” section above.

Example:

moment().format("YYYY Do MM")

Moment provides some constants you can use instead of writing your own format:

Validating a date

Any date can be checked for validity using the isValid() method:

moment('2018-13-23').isValid() //false
moment('2018-11-23').isValid() //true

Time ago, time until date

Use fromNow(). Strings are localized:

moment('2016-11-23').fromNow() //2 years ago
moment('2018-05-23').fromNow() //a month ago
moment('2018-11-23').fromNow() //in 5 months

if you pass true to fromNow(), it just shows the difference, without reference to future/past.

moment('2016-11-23').fromNow(true) //2 years
moment('2018-05-23').fromNow(true) //a month
moment('2018-11-23').fromNow(true) //5 months

Manipulate a date

You can add or subtract any amount of time to a date:

moment('2016-11-23').add(1, 'years')
moment('2016-11-23').subtract(1, 'years')

You can use those values:

• years
• quarters
• months
• weeks
• days
• hours
• minutes
• seconds
• milliseconds

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