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JayCooper's avatar
JayCooper
Community Member
3 years ago

JavaScript to Subtract Days from Current Date

I'm working on a course that involves sorting juveniles with one of the criteria being their age.  I'm looking to display each child's age based on the current date, minus X number of days so that t...
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JayCooper's avatar
JayCooper
Community Member
3 years ago

Jurgen,

Thank you for the help.  The problem with breaking the new Date up this way is how to make adjustments if the date is at the beginning of the month or year.  

I appreciate your help.

v/r

Jay

Jürgen_Schoene_'s avatar
Jürgen_Schoene_
Community Member
3 years ago

you have nothing to adjust - the javascript library does all adjustments automaticly,
this is modern JavaScript

const years = -18; // 18 years back
const days  = +10; // 10 day forward

const options = { 
  weekday: 'long',
  year: 'numeric', 
  month: 'long', 
  day: 'numeric' 
};

const event = new Date( 'December 28, 2023 23:15:30');
console.log( "1 - now", event.toLocaleDateString('en-US', options) )

event.setFullYear(event.getFullYear() + years);
console.log( "2 - year", years, event.toLocaleDateString('en-US', options) )

event.setDate(event.getDate() + days)
console.log( "3 - days", days, event.toLocaleDateString('en-US', options) )

result:

  • "1 - now", "Thursday, December 28, 2023"
  • "2 - year", -18, "Wednesday, December 28, 2005"
  • "3 - days", 10, "Saturday, January 7, 2006"

or with February 29

const event = new Date( 'February 29, 2024 23:15:30');
console.log( "1 - now", event.toLocaleDateString('en-US', options) )

event.setFullYear(event.getFullYear() + years);
console.log( "2 - year", years, event.toLocaleDateString('en-US', options) )

event.setDate(event.getDate() + days)
console.log( "3 - days", days, event.toLocaleDateString('en-US', options) )

result:

  • "1 - now", "Thursday, February 29, 2024"
  • "2 - year", -18, "Wednesday, March 1, 2006"
  • "3 - days", 10, "Saturday, March 11, 2006"


    or the same date, but -16 years
  • "1 - now", "Thursday, February 29, 2024"
  • "2 - year", -16, "Friday, February 29, 2008"
  • "3 - days", 10, "Monday, March 10, 2008"

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