How to Calculate the Number of Days Between two Dates in TypeScript ?

In TypeScript, calculating the number of days between two dates is a common task in many applications. Whether you’re working with date ranges, scheduling, or performing date-based calculations, knowing how to accurately determine the difference in days between two dates is essential.

Different approaches to achieve this in TypeScript:

Using Two different dates

This approach involves creating Date objects for the two dates you want to compare and then calculating the difference in milliseconds between them. Afterward, you can convert this difference into days.

Syntax :

const date: Date = new Date("//date you want")

Example: The following JavaScript program will illustrate the process of finding the number of days between two dates.

Javascript

// Create Date objects representing the two dates
const date1: Date = new Date('2024-01-15');
const date2: Date = new Date('2024-02-06');

// Calculate the difference in
// milliseconds between the two dates
const differenceInMs: number =
    Math.abs(date2.getTime() - date1.getTime());

// Define the number of milliseconds in a day
const millisecondsInDay: number = 1000 * 60 * 60 * 24;

// Calculate the difference in days by
// dividing the difference in milliseconds by
// milliseconds in a day
const differenceInDays: number =
    Math.floor(differenceInMs / millisecondsInDay);

// Output the result
console.log(
    'Number of days between the two dates:', differenceInDays);

Output :

Number of days between the two dates: 22

Using moment.js library

This method provides a convenient and concise way to calculate the number of days between two dates using moment.js, a popular library for date manipulation in JavaScript and TypeScript, for using moment.js library one need to install and configure node.js and then install the moment package in order to use.

Syntax:

npm install moment
import * as moment from 'moment';

Example: The following JavaScript program will illustrate the process of finding the number of days between two dates.

Javascript

// Import the moment.js library using
// the import statement.
import * as moment from 'moment';

function daysBetweenDates(date1: string, date2: string): number {

    // Create moment object for the start date.
    const startMoment = moment(date1);

    // Create moment object for the end date.
    const endMoment = moment(date2);

    // using the diff() method with 'days' as
    // the second parameter.
    // This method returns the difference between
    // the two moments in days.

    const daysDifference =
        endMoment.diff(startMoment, 'days');
    return daysDifference;
}

const startDate = '2024-01-01';
const endDate = '2024-02-08';

const daysDifference =
    daysBetweenDates(startDate, endDate);

console.log(
    "Number of days between the two dates:", daysDifference);

Output:

Number of days between the two dates: 38