Increment 7 days to a date in Google Sheets

Question

Explanation of my my objective : By the press of a button in my google sheets, add 7 days to a currently exsting date in a cell.

What currently happens : When I press to run my script instead of adding 7 days it simply writes 7 at then end.

My script :

function IncrementW() {
  var spreadsheet = SpreadsheetApp.getActive();
  SpreadsheetApp.getActiveSheet().getActiveCell().setValue(SpreadsheetApp.getActiveSheet().getActiveCell().getValue() + 7);
};

What the output gives me:

From: 7/12/2020 to >> Sun Jul 12 2020 00:00:00 GMT-0400 (Eastern Daylight Time)7

What my output should be :

From: 7/12/2020 to >> 7/19/2020

Thank you for the help.

Answer 1

getValue() returns a Date object(which gets converted to string , when used with the + operator). Use setDate() to setDate:

function IncrementW() {
  const spreadsheet = SpreadsheetApp.getActive();
  const cell = spreadsheet.getActiveSheet().getActiveCell();
  const dt = cell.getValue();
  dt.setDate(dt.getDate() + 7);
  cell.setValue(dt);
};