How to add days to a date from Google Sheets?

Question

I can\'t figure out how to add days to a date from Google Sheets with Google Apps Script.

for (var i = 0; i < data.length; ++i) {
    var row = data[i];
          


        

Answer 1

There are probably many ways to do that, here are 2 of them

1. Knowing that native value of JavaScript Date are milliseconds, you can add n times 3600000*24 milliseconds to this native value, n being the number of days.
2. or you can get the day value, add n to this value and rebuild the date with that. To get the day simply use getDate(). See doc on JS date here.

Below is a simple demo function that uses both methods and shows results in the logger :

function myFunction() {
  var data = SpreadsheetApp.getActive().getActiveSheet().getDataRange().getValues();
  for (var i = 0; i < data.length; ++i) {
    var row = data[i];
    var car = row[1];
    var date = new Date(row[2]); // make the sheet value a date object
    Logger.log('original value = '+date);
    Logger.log('method 1 : '+new Date(date.getTime()+5*3600000*24));
    Logger.log('method 2 : '+new Date(date.setDate(date.getDate()+5)));
  }
}