javascript date add days not working

stackoverflow.com › questions › 563406 › how-to-add-days-to-date

You can create one using Date.prototype.setDate():

Date.prototype.addDays = function(days) {
    var date = new Date(this.valueOf());
    date.setDate(date.getDate() + days);
    return date;
}

var date = new Date();

console.log(date.addDays(5));

This takes care of automatically incrementing the month if necessary, as noted here. For example:

8/31 + 1 day will become 9/1.

The problem with using setDate directly is that it's a mutator and that sort of thing is best avoided. ECMA saw fit to treat Date as a mutable class rather than an immutable structure.

Answer from AnthonyWJones on Stack Overflow

Stack Overflow

stackoverflow.com › questions › 563406 › how-to-add-days-to-date

javascript - How to add days to Date? - Stack Overflow

Top answer

1 of 16

1850

You can create one using Date.prototype.setDate():

Date.prototype.addDays = function(days) {
    var date = new Date(this.valueOf());
    date.setDate(date.getDate() + days);
    return date;
}

var date = new Date();

console.log(date.addDays(5));

This takes care of automatically incrementing the month if necessary, as noted here. For example:

8/31 + 1 day will become 9/1.

The problem with using setDate directly is that it's a mutator and that sort of thing is best avoided. ECMA saw fit to treat Date as a mutable class rather than an immutable structure.

2 of 16

1171

Correct Answer:

function addDays(date, days) {
  var result = new Date(date);
  result.setDate(result.getDate() + days);
  return result;
}

Incorrect Answer:

This answer sometimes provides the correct result but very often returns the wrong year and month. The only time this answer works is when the date that you are adding days to happens to have the current year and month.

// Don't do it this way!
function addDaysWRONG(date, days) {
  var result = new Date(); // not instatiated with date!!! DANGER
  result.setDate(date.getDate() + days);
  return result;
}

Proof / Example

Check this JsFiddle

// Correct
function addDays(date, days) {
    var result = new Date(date);
    result.setDate(result.getDate() + days);
    return result;
}

// Bad Year/Month
function addDaysWRONG(date, days) {
    var result = new Date();
    result.setDate(date.getDate() + days);
    return result;
}

// Bad during DST
function addDaysDstFail(date, days) {
    var dayms = (days * 24 * 60 * 60 * 1000);
    return new Date(date.getTime() + dayms);    
}

// TEST
function formatDate(date) {
    return (date.getMonth() + 1) + '/' + date.getDate() + '/' + date.getFullYear();
}

$('tbody tr td:first-child').each(function () {
    var (this);
    var ('<td/>').insertAfter($in).addClass("answer");
    var $outFail = $('<td/>').insertAfter(outDstFail = $('<td/>').insertAfter($outFail);
    var date = new Date($in.text());
    var correctDate = formatDate(addDays(date, 1));
    var failDate = formatDate(addDaysWRONG(date, 1));
    var failDstDate = formatDate(addDaysDstFail(date, 1));

    $out.text(correctDate);
    $outFail.text(failDate);
    $outDstFail.text(failDstDate);
    $outFail.addClass(correctDate == failDate ? "right" : "wrong");
    $outDstFail.addClass(correctDate == failDstDate ? "right" : "wrong");
});

body {
    font-size: 14px;
}

table {
    border-collapse:collapse;
}
table, td, th {
    border:1px solid black;
}
td {
    padding: 2px;
}

.wrong {
    color: red;
}
.right {
    color: green;
}
.answer {
    font-weight: bold;
}

<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js"></script>
<table>
    <tbody>
        <tr>
            <th colspan="4">DST Dates</th>
        </tr>
        <tr>
            <th>Input</th>
            <th>+1 Day</th>
            <th>+1 Day Fail</th>
            <th>+1 Day DST Fail</th>
        </tr>
        <tr><td>03/10/2013</td></tr>
        <tr><td>11/03/2013</td></tr>
        <tr><td>03/09/2014</td></tr>
        <tr><td>11/02/2014</td></tr>
        <tr><td>03/08/2015</td></tr>
        <tr><td>11/01/2015</td></tr>
        <tr>
            <th colspan="4">2013</th>
        </tr>
        <tr>
            <th>Input</th>
            <th>+1 Day</th>
            <th>+1 Day Fail</th>
            <th>+1 Day DST Fail</th>
        </tr>
        <tr><td>01/01/2013</td></tr>
        <tr><td>02/01/2013</td></tr>
        <tr><td>03/01/2013</td></tr>
        <tr><td>04/01/2013</td></tr>
        <tr><td>05/01/2013</td></tr>
        <tr><td>06/01/2013</td></tr>
        <tr><td>07/01/2013</td></tr>
        <tr><td>08/01/2013</td></tr>
        <tr><td>09/01/2013</td></tr>
        <tr><td>10/01/2013</td></tr>
        <tr><td>11/01/2013</td></tr>
        <tr><td>12/01/2013</td></tr>
        <tr>
            <th colspan="4">2014</th>
        </tr>
        <tr>
            <th>Input</th>
            <th>+1 Day</th>
            <th>+1 Day Fail</th>
            <th>+1 Day DST Fail</th>
        </tr>
        <tr><td>01/01/2014</td></tr>
        <tr><td>02/01/2014</td></tr>
        <tr><td>03/01/2014</td></tr>
        <tr><td>04/01/2014</td></tr>
        <tr><td>05/01/2014</td></tr>
        <tr><td>06/01/2014</td></tr>
        <tr><td>07/01/2014</td></tr>
        <tr><td>08/01/2014</td></tr>
        <tr><td>09/01/2014</td></tr>
        <tr><td>10/01/2014</td></tr>
        <tr><td>11/01/2014</td></tr>
        <tr><td>12/01/2014</td></tr>
        <tr>
            <th colspan="4">2015</th>
        </tr>
        <tr>
            <th>Input</th>
            <th>+1 Day</th>
            <th>+1 Day Fail</th>
            <th>+1 Day DST Fail</th>
        </tr>
        <tr><td>01/01/2015</td></tr>
        <tr><td>02/01/2015</td></tr>
        <tr><td>03/01/2015</td></tr>
        <tr><td>04/01/2015</td></tr>
        <tr><td>05/01/2015</td></tr>
        <tr><td>06/01/2015</td></tr>
        <tr><td>07/01/2015</td></tr>
        <tr><td>08/01/2015</td></tr>
        <tr><td>09/01/2015</td></tr>
        <tr><td>10/01/2015</td></tr>
        <tr><td>11/01/2015</td></tr>
        <tr><td>12/01/2015</td></tr>
    </tbody>
</table>

Mastering JS

masteringjs.io › tutorials › fundamentals › date-add-days

JavaScript Add Days to Date - Mastering JS

const now = new Date(); // Add 37 days to now, and zero out hours, minutes, seconds, milliseconds now.setDate(now.getDate() + 37); now.setHours(0, 0, 0, 0); Working with JavaScript dates can be inelegant because most date methods return timestamps, not dates, so chaining isn't possible.

Videos

youtube.com

How to add days to current Date using JavaScript - YouTube

March 2, 2023

01:33

YouTube

How to add days to a JavaScript date - YouTube

How to add days to date using Javascript - YouTube

April 29, 2022

m.youtube.com

JavaScript add days to date

youtube.com

Create a Year Day prototype for Date in JavaScript - YouTube

September 13, 2024

View all

GeeksforGeeks

geeksforgeeks.org › javascript › how-to-add-days-to-date-in-javascript

How to Add Days to Date in JavaScript? - GeeksforGeeks

July 23, 2025 - The setDate() method allows you to modify the day of the month for a Date object. To use this method, you start by creating a Date object that represents the current date. You can then add a specific number of days to this date and assign the result to a new Date object.

Stack Overflow

stackoverflow.com › questions › 67354616 › adding-days-to-a-date-object-in-javascript-is-not-working-properly

Adding days to a Date object in JavaScript is not working properly - Stack Overflow

Top answer

1 of 5

The problem is that when you are initializing a new date object using new Date(), the date object is initialized with the current date. When you increment the days using currentDate.getDate() + offset the day of the month is first set to that of currentDate and incremented by offset but the month from which it is incremented is the current month. Try this one.

var currentDate = new Date("2021-04-27T15:30:27.588+0000");
console.log(currentDate); // this prints Wed Apr 28 2021 00:00:00 GMT+1000 (Australian Eastern Standard Time)

// want to add 45 days to my date
var offset = 45;
var xDate = new Date("2021-04-27T15:30:27.588+0000");
xDate.setDate(currentDate.getDate() + offset);
console.log(xDate);

2 of 5

1 day is equal to 86,400,000 milliseconds. You can multiply that value by 45 and add it to your date:

var currentDate = new Date("2021-04-27T15:30:27.588+0000");
console.log(currentDate);

// Add 45 days
var offset = 45;
var xDate = new Date(currentDate.getTime() + offset * 86400000);
console.log(xDate);

CoreUI

coreui.io › answers › how-to-add-days-to-date-in-javascript

How to add days to date in JavaScript · CoreUI

September 30, 2025 - The most reliable approach is using the setDate() method which automatically handles month boundaries, year transitions, and leap years. This native JavaScript method eliminates edge case bugs that plague manual date arithmetic.

GitHub

github.com › Budibase › budibase › discussions › 10473

Adding days to a date in JS using moment · Budibase/budibase · Discussion #10473

Author Budibase

Top answer

1 of 1

Hey @SICUFI,

The date.helper doesn't have the function within to do what you are wanting, its limited to time zoning and formatting the date. You can however achieve this with something similar to the following:

The result can be seen below:

I hope this helps!

Full Stack Express

fullstackexpress.io › c › how-to-add-days-to-a-date-object-in-javascript

How to Add Days to a Date Object in JavaScript | Full Stack Express

const addDays = (date, days) => { const newDate = new Date(date); newDate.setDate(newDate.getDate() + days); return newDate; }; If we directly call the setDate() method on our date object, then the date would be mutated.

Futurestud.io

futurestud.io › tutorials › add-days-to-a-date-in-javascript-or-node-js

Add Days to a Date in JavaScript or Node.js

/** * Returns a date instance with added `days`. * * @param {Number} days - the number of days to add * @param {Date} date - the date adding the given `days` * * @returns {Date} */ function addDays (days, date = new Date()) { date.setDate(date.getDate() + days) return date } Also, a nice part of JavaScript’s setDate function is the automatic handling of the month and year changes. For example, when adding a day to August 31st you’re receiving September 1st.

Find elsewhere

Google Bing Mojeek

W3docs

w3docs.com › javascript

How to Add Days to JavaScript Date

In this tutorial, you will learn an easy way of adding days to Javascript Date with setDate() and getDate() inbuilt functions to set and get the day of the month represented by the Date object. Here is a utility function that creates a date object and adds seven days to it, to have a date object representing next week.

Stack Overflow

stackoverflow.com › questions › 15495728 › whats-wrong-on-adding-days-at-this-date-function

javascript - What's wrong on adding Days at this Date function? - Stack Overflow

Top answer

1 of 5

My browser (Chrome) prints "Invalid date", but apparently yours interprets the initializing date in mm/dd/yyyy format instead of dd/mm/yyyy. Therefore it thinks it's the 3rd day of the 24th month of 2013, which is January 3rd, 2015.

I'm not sure why it would print it as January 6th if you add 7 days to it.

The safest way is to give the numbers explicitly:

var dat = new Date( 2013, 2, 24 );

2 of 5

Change the format of your date to put the day after the month:

var dat = new Date("03/24/2013");
dat.setDate(dat.getDate() + 7);
console.log(dat)

For me this returns:

Sun Mar 31 2013 00:00:00 GMT+0000 (GMT Standard Time)

The Valley of Code

thevalleyofcode.com › how-to-add-days-date-javascript

How to add days to a date in JavaScript

Working with dates in JavaScript is always kind of fun. I wrote on this topic countless times, but there’s always more to learn. ... Today I have the solution to this problem: you have a Date object in JavaScript, and you want to add some days to it.

GitHub

github.com › orgs › date-fns › discussions › 2742

Adding and removing one day using addDays doesn't return original date · date-fns · Discussion #2742

Top answer

1 of 1

Sorry everyone, I realized something interesting just now and it's not a bug after all.

The datetime you were landing on actually doesn't even technically exist because of the DST shift. The JS Date object resolves it to the next hour automatically.

process.env.TZ = 'CET';

console.log(new Date(2060, 2, 28, 1, 59, 59, 999).toString());
console.log(new Date(2060, 2, 28, 2).toString());
console.log(new Date(2060, 2, 28, 2, 30).toString()); // resolves to 3:30 am!
console.log(new Date(2060, 2, 28, 3).toString());

// Sun Mar 28 2060 01:59:59 GMT+0100 (GMT+01:00)
// Sun Mar 28 2060 03:00:00 GMT+0200 (GMT+02:00)
// Sun Mar 28 2060 03:30:00 GMT+0200 (GMT+02:00)
// Sun Mar 28 2060 03:00:00 GMT+0200 (GMT+02:00)

DEV Community

dev.to › hugo__df › add-days-to-a-date-in-vanilla-javascript-4p2l

Add days to a Date in vanilla JavaScript - DEV Community

May 3, 2019 - While it would be very easy to reach for moment.js or another date manipulation library (date-fns, luxon, dayjs) to do something as simple as adding days to a Date in JavaScript, writing a short helper function might just be easier. function addDays(date, days) { const copy = new Date(Number(date)) copy.setDate(date.getDate() + days) return copy } const date = new Date(); const newDate = addDays(date, 10); const date = new Date(); date.setDate(date.getDate() + 10); This actually works as expected, eg.

Code with Hugo

codewithhugo.com › add-date-days-js

Add days to a Date in vanilla JavaScript · Code with Hugo

May 1, 2020 - While it would be very easy to reach for moment.js or another date manipulation library (date-fns, luxon, dayjs) to do something as simple as adding days to a Date in JavaScript, writing a short helper function might just be easier. ... function addDays(date, days) { const copy = new Date(Number(date)) copy.setDate(date.getDate() + days) return copy } const date = new Date(); const newDate = addDays(date, 10); const date = new Date(); date.setDate(date.getDate() + 10); const date = new Date(); date.setDate(date.getDate() + 1); const date = new Date(); date.setDate(date.getDate() + 7); This actually works as expected, eg.

Stack Overflow

stackoverflow.com › questions › 3818193 › how-to-add-number-of-days-to-todays-date

javascript - How to add number of days to today's date? - Stack Overflow

Top answer

1 of 16

664

You can use JavaScript, no jQuery required:

var someDate = new Date();
var numberOfDaysToAdd = 6;
var result = someDate.setDate(someDate.getDate() + numberOfDaysToAdd);
console.log(new Date(result))

2 of 16

178

This is for 5 days:

var myDate = new Date(new Date().getTime()+(5*24*60*60*1000));

You don't need JQuery, you can do it in JavaScript, Hope you get it.

Tutorial Republic

tutorialrepublic.com › faq › how-to-add-days-to-current-date-in-javascript.php

How to Add Days to Current Date in JavaScript

You can simply use the setDate() method to add number of days to current date using JavaScript. Also note that, if the day value is outside of the range of date values for the month, setDate() will update the Date object accordingly (e.g. if ...

Knack

forums.knack.com › ask the community › get answers

JS problem with adding dates dates to all months with 31 days - Get Answers - Knack Community Forum

February 5, 2024 - I am trying to take in a date and get the Javascript to verify which quarter that date is in then output the date 1st day of the next quarter. My code works except for when someone enters the last day of the month on dates that end on the 31st. I figured out this may have something to do with timezones so I get UTC values instead of actual values so I remove the timezone out of the equation.

MSR

rajamsr.com › home › how to add days to date in javascript with 3 examples

How to Add Days to Date in JavaScript With 3 Examples | MSR - Web Dev Simplified

January 18, 2024 - // Creates a Date object with January 1, 2023, 00:00:00 let date1 = new Date(2023, 0, 1); // Creates a Date object with January 11, 2023, 00:00:00 let date2 = new Date(2023, 0, 11); console.log(date1.getTime()); // Output: "1672531200000" console.log(date2.getTime()); // Output: "1673344800000" console.log(date1.getTime() < date2.getTime()); // Output: "true" (date1 is before date2) console.log(date1.getTime() > date2.getTime()); // Output: "false" (date1 is not after date2) console.log(date1.getTime() === date2.getTime()); // Output: "false" (date1 is not equal to date2) One of the challenges

DEV Community

dev.to › lavary › how-to-add-days-to-a-date-in-javascript-without-a-library-3795

How to add days to a date in JavaScript (without a library) - DEV Community

February 5, 2023 - To add a few days to a date in JavaScript, you need to use setDate() on the Date object and increment the current day of the month by one or more days.

Delft Stack

delftstack.com › home › howto › javascript › javascript add days to date

How to Add Days to Current Date in JavaScript | Delft Stack

February 2, 2024 - This tutorial will introduce how to add a new day to the current date or a custom date in JavaScript. We will first introduce what is Date and different methods in JavaScript Date class. In JavaScript, the Date class is basically the number of milliseconds that passed since midnight on January 1, 1970, UTC. It is not ...