How to add Days to a Date in JavaScript

Working with dates in JavaScript has historically been a challenge.

One of most commonly needed operations is how to add a number of days to a date to get a new date.

In this post, we'll look at the easiest way you can add a number of days to another date

Adding days to a date

Let's first start by creating a date object.

JAVASCRIPT
const date = new Date();

To increase the days on a Date, we can take advantage of the Date object's getDate() and setDate() methods.

More specifically, we can first get the original date's day, and then add the number of days we want to add to it.

Here's a long-form example of how we can add a number of days to a date:

JAVASCRIPT
const date = new Date();
const originalDay = date.getDate();

const daysToAdd = 5;
const newDay = originalDay + daysToAdd;

date.setDate(newDay);

We can turn this into a reusable function that we can call whenever we want to add any number of days to a date.

JAVASCRIPT
const addDays = (date, daysToAdd) => {
    date.setDate(date.getDate() + daysToAdd);
};

const date = new Date();

addDays(date, 5);

Now you can easily add a week to a date by calling the function with addDays(date, 7), for example:

JAVASCRIPT
const date = new Date();

addDays(date, 7);

Conclusion

In this post, we created a function that lets us add any number of days to a date by modifying the date object.

We took advantage of the getDate() and setDate() to manipulate the original Date.

Hopefully, you've found this content useful and enjoyed reading it!

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