Moment.js using with System.js

Last Updated : 26 Apr, 2025

Moment.js is a popular JavaScript library for working with dates and times. It provides a simple and powerful API for parsing, validating, manipulating, and formatting dates and times.

System.js is a dynamic module loader for JavaScript, which allows you to import and load modules as needed at runtime. It is particularly useful for working with large and complex applications that require a modular structure.

In Node.js, Moment.js can be used in conjunction with System.js to perform a variety of tasks involving dates and times.

Description: When using Moment.js with System.js in Node.js, you can leverage the powerful date and time manipulation capabilities of Moment.js to perform a variety of tasks, while also taking advantage of the modular structure provided by System.js. For example, you might use Moment.js to parse and validate dates and times, or to perform calculations and transformations on dates and times, while using System.js to manage the dependencies between your various modules.

Syntax: To use Moment.js with System.js in Node.js, you will need to install both libraries using npm.

npm install moment
npm install systemjs

Then, you can import the Moment.js library into your Node.js code using System.js:

Javascript

const moment = require('moment'); 
  
System.import(moment).then((moment) => { 
    // use the Moment.js library here 
});

From there, you can use the various methods and functions provided by the Moment.js library to perform your desired operations.

Parameters: The parameters for the various methods and functions provided by the Moment.js library will depend on the specific method or function being used. However, in general, most methods and functions will take one or more date or time values as arguments, and may also accept additional options or configurations as needed.

Return Value: The return value for the various methods and functions provided by the Moment.js library will also depend on the specific method or function being used. However, in general, most methods and functions will return a new Moment.js object representing the resulting date or time value.

Example 1: This example will use the Moment.js moment() function to parse and validate a date string, and then use the isValid() method to check whether the resulting date is valid:

Javascript

const moment = require('moment'); 
  
System.import(moment).then((moment) => { 
    const dateString = '2022-12-27'; 
    const date = moment(dateString, 'YYYY-MM-DD'); 
    if (date.isValid()) { 
        console.log(`${dateString} is a valid date`); 
    } else { 
        console.log(`${dateString} is not a valid date`); 
    } 
});

Output:

2022-12-27 is a valid date

Explanation: This code checks whether the date object, which is a Moment.js object representing a date and time, is valid using the isValid() method. If the date is valid, it logs a message to the console indicating that the date is valid. If the date is not valid, it logs a message to the console indicating that the date is not valid. The dateString variable is used to include the original date string in the output messages.

Example 2: In this example, we will use the Moment.js `diff()` method to calculate the number of days between two dates:

Javascript

const moment = require('moment'); 
  
System.import(moment).then((moment) => { 
    const date1 = moment('2022-12-27', 'YYYY-MM-DD'); 
    const date2 = moment('2023-01-01', 'YYYY-MM-DD'); 
  
    const days = date2.diff(date1, 'days'); 
  
    console.log( 
        `There are ${days} days between ${date1.format('YYYY-MM-DD')}  
         and ${date2.format('YYYY-MM-DD')}`); 
});

Output:

There are 4 days between 2022-12-27 and 2023-01-01

Explanation: The output will be a string of the form ‘There are X days between YYYY-MM-DD and YYYY-MM-DD’, where X is the number of days between the two dates, and YYYY-MM-DD are the formatted dates.

Reference: https://momentjs.com/docs/#/use-it/system-js/