Using getTime in a For loop in google sheets script - datetime

Question

I am trying to run a 'for' loop that looks like this:
function runMultipleDates() {
var ss = SpreadsheetApp.getActiveSpreadsheet();
//9/26/2018 is 1569477600000 and 2/28/2019 is 1551337200000; 9/21/2018 is 1537509600000
for (var date1 = 1537596000000 /*9/21/2018*/; date1 < 1569477600000 /*9/26/2018*/; date1 +=86400000) {
//runEverything();
var date2 = new Date();
date2 = date2.setTime(date1);
ss.getSheetByName('Time Range').getRange("A3").setValue(date2);
};
};
My goal is to run a function called "runEverything()" that reference a date located in cell A3 of a sheet called 'Time Range'. As long as the date in cell A3 is less that 9/26/2018, the for loop should run my function 'runEverything' and then set a new date in A3. When I do my test loop, the setValue(date2) returns a numeric value rather than a date in that cell (A3). Can someone point out how I can return the date format rather than the numeric value of date? if there is a more elegant way to achieve this, I am all ears!
Thank you for your insight!

Answer 1

You want to use the date string instead of the unix time
If my understanding is correct, how about the following script? Please think of this as just one of several possible answers.
Sample script:
function runMultipleDates() {
var ss = SpreadsheetApp.getActiveSpreadsheet();
var start = new Date("2018-09-29"); // <--- 1538200800000
var end = new Date("2018-10-05"); // <--- 1538719200000
var step = 1; // 1 day (86400000)
for (var date1 = start; date1 <= end; date1.setDate(date1.getDate() + step)) {
runEverything();
var date2 = new Date(date1.getTime());
date2.setDate(date2.getDate() + 1);
ss.getSheetByName('Time Range').getRange("A3").setValue(date2);
};
}
This script brings the same result with the script of your answer.
When the script is run, 10/06/2018 is put to the cell "A3".
References:
getDate()
setDate()

Answer 2

Tanaike suggested using new Date(date2) in the setValue() and it worked. My final script is something like this:
function runMultipleDates() {
var ss = SpreadsheetApp.getActiveSpreadsheet();
for (var date1 = 1538200800000 ; date1 <= 1538719200000; date1 +=86400000) {
runEverything();
var date2 = new Date();
date2 = date2.setTime(date1+86400000);
ss.getSheetByName('Time Range').getRange("A3").setValue(new Date(date2));
};