JS Dates

JavaScript Dates: A Beginner's Guide

In order to work with dates and times in JavaScript, we use the built-in Date object. This powerful object comes with many methods and constructors to create, format, and manipulate dates.

1. Creating Date Objects

There are several different ways to create a new date object. Let's explore the most common constructors.

Method 1: new Date()

The simplest way to create a date is to call new Date() with no arguments. This will create a Date object containing the current date and time according to the user's system.

let currentDateTime = new Date();
console.log(currentDateTime);

Method 2: Date.now()

There is a static built-in method, Date.now(), that returns the current date and time represented as the number of milliseconds since January 1st, 1970 UTC. This arbitrary date is known as the Unix epoch.

let now2 = Date.now();
console.log(now2);

Method 3: new Date(milliseconds)

You can create a specific date by passing a number of milliseconds into the constructor. This will create a date that is that many milliseconds after the Unix epoch.

// Create a date for 1000 milliseconds (1 second) after the epoch
let milliDate = new Date(1000);
console.log(milliDate); // 1970-01-01T00:00:01.000Z

Method 4: new Date(dateString)

JavaScript can also convert many different string formats into a Date object.

let stringDate = new Date("Sat Jun 05 2021 12:40:12 GMT+0200");
console.log(stringDate);

Method 5: new Date(year, month, day, ...)

Finally, you can specify a precise date and time by passing the individual components as arguments to the constructor.

// new Date(year, month, day, hours, minutes, seconds, ms)
// Here, month '1' means February!
let specificDate = new Date(2022, 1, 10, 12, 10, 15, 100);
console.log(specificDate); // 2022-02-10T11:10:15.100Z (adjusts for timezone)