Error in Date Differences in Google Sheets App Script - google-apps-script

Question

In Googlesheets's "Sheet1", dates are manually entered in Column A.
When I enter a date in column A, Column B should be filled with the difference between new Date() and the date just entered in Column A.
Until now, I have tried the following code:
function onEdit() {
var s2=SpreadsheetApp.getActive().getSheetByName("Sheet1");
var lastRow=s2.getLastRow();
var entry_date =s2.getRange(lastRow, 1).getValue();
var now = new Date();
var diff = now-entry_date;
s2.getRange(lastRow, 2).setValue(diff);
}
However, Column B is giving very random results and I am not being able to understand. I just need the date difference to be filled in column B in the same row.

Answer 1

The result is looking odd to you because you are expecting it in days (the way the sheet would show it) but the script is showing you the result in milliseconds. To get the answer in number-of-days, try this:
function onEdit() {
var s2 = SpreadsheetApp.getActive().getSheetByName("Sheet1");
var lastRow = s2.getLastRow();
var entry_date = s2.getRange(lastRow, 1).getValue();
var now = new Date();
var diff = (now-entry_date) / (24 * 60 * 60 * 1000); // Divide by number of milliseconds in a day
s2.getRange(lastRow, 2).setValue(diff);
}
This will give you an output that looks like 3.4567 (days + fraction of day in milliseconds).
To get it rounded down to just the number of days, you could try this:
function onEdit() {
var s2 = SpreadsheetApp.getActive().getSheetByName("Sheet1");
var lastRow = s2.getLastRow();
var entry_date = s2.getRange(lastRow, 1).getValue();
var now = new Date();
var diff = (now-entry_date) / (24 * 60 * 60 * 1000); // Divide by number of milliseconds in a day
diff = Math.floor(diff); // Round down
s2.getRange(lastRow, 2).setValue(diff);
}