Subtract days from a date in JavaScript

Answer 1

If you want it all on one line instead.

5 days from today

//past
var thirtyDaysAgo = new Date(new Date().setDate(new Date().getDate() - 5));
//future
var thirtyDaysInTheFuture = new Date(new Date().setDate(new Date().getDate() + 5));

5 days from a specific date

 var pastDate = new Date('2019-12-12T00:00:00');

 //past
 var thirtyDaysAgo = new Date(new Date().setDate(pastDate.getDate() - 5));
 //future
 var thirtyDaysInTheFuture = new Date(new Date().setDate(pastDate.getDate() + 5));

I wrote a function you can use.

function AddOrSubractDays(startingDate, number, add) {
  if (add) {
    return new Date(new Date().setDate(startingDate.getDate() + number));
  } else {
    return new Date(new Date().setDate(startingDate.getDate() - number));
  }
}

console.log('Today : ' + new Date());
console.log('Future : ' + AddOrSubractDays(new Date(), 5, true));
console.log('Past : ' + AddOrSubractDays(new Date(), 5, false));