Finding date by subtracting X number of days from a particular date in Javascript

Question

Hi All,

I want to find date by subtracting X number of days from a particular date in JavaScript. My JavaScript function accepts 2 parameters. One is the date value and the other is the number of days that needs to be subtracted.

For example, I pass my argument date as 27 July 2009 and i pass my other argument as 3. So i want to calculate the date 3 days before 27 July 2009. So the resultant date that we should get is 24 July 2009. How is this possible in JavaScript. Thanks for any help.

Answer 1

Simply:

yourDate.setDate(yourDate.getDate() - daysToSubtract);

Answer 2

Here's an example, however this does no kind of checking (for example if you use it on 2009/7/1 it'll use a negative day or throw an error.

function subDate(o, days) {
// keep in mind, months in javascript are 0-11
return new Date(o.getFullYear(), o.getMonth(), o.getDate() - days);;
}

Answer 3

This is what I would do. Note you can simplify the expression, I've just written it out to make it clear you are multiplying the number of days by the number of milliseconds in a day.

 var newDate = new Date( yourDate.getTime() - (days * 24 * 60 * 60 * 1000) );

Answer 4

Just another option, which I wrote:

DP_DateExtensions Library

It's probably overkill if ALL you want to do is one calculation, but if you're going to do more date manipulation you might find it useful.

Supports date/time formatting, date math (add/subtract date parts), date compare, date parsing, etc.