How to Clone a Date object in JavaScript

Clone a Date object in JavaScript #

To clone a date object:

1. Use the getTime() method to get the number of milliseconds since the Unix Epoch.
2. Pass the result to the Date() constructor.
3. For example, const dateClone = new Date(date.getTime()).

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const date = new Date();
console.log(date); // 👉️ Mon Jan 24 2022 11:32:39

const dateClone = new Date(date.getTime());

console.log(dateClone); // 👉️ Mon Jan 24 2022 11:32:39

The getTime method returns a number that represents the milliseconds elapsed between midnight of the 1st of January 1970 and the given date.

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// 👇️ 1643017048020
console.log(new Date().getTime());

The Date() constructor can be passed a timestamp as a parameter and creates a new Date object storing the specified date and time.

It's a best practice to clone a date, before using any of the methods that mutate the Date object in place, e.g. set*.

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const date = new Date('2022-09-24T09:25:00');

// 👇️ Sap Sep 24 2022 09:25:00
console.log(date);

const dateClone = new Date(date.getTime());

// 👇️ Sap Sep 24 2022 09:25:00
console.log(dateClone);

dateClone.setHours(0, 0, 0, 0);

// 👇️ Sat Sep 24 2022 00:00:00
console.log(dateClone);

// 👇️ Sat Sep 24 2022 09:25:00 (didn't change original)
console.log(date);

We used the getTime() method to get a timestamp of the date and passed it to the Date() constructor to get a Date object.

In the example, we used the setHours() method to change the hour, minutes, seconds and milliseconds of the cloned date.

Creating a clone of the date before using the method allows us to preserve the original.