Returning Dates In A Formatted Format (Iteration) - google-apps-script

Question

I am trying to create tabs with each tab name being the date of the start of each week in the year. So, "Jan 01" then "Jan 08" then "Jan 14" etc.
Essentially, taking x date then adding +7 days and returning that value as a date 7 days from x date.
function CreateWeekTabs(){
var TotalsSheet = spreadsheet.getSheetByName("Totals");
var StartingWeek = new Date(TotalsSheet.getRange("B1").getValue()); //Typically always "Jan 01" shwon. Cell Formatting is MMM DD. Cell Value is 01/01/2019
var CurrentWeek = new Date();
var NextWeek = new Date();
spreadsheet.toast("Please wait...","Creating Tabs");
for (var WeekNum = 1;WeekNum <= 2;WeekNum++){
var DayIncrease = 7 - (7 * WeekNum); //Should produce 0,7,14,21,28.... So first iteration won't increase any value from Jan 01.
CurrentWeek.setDate(StartingWeek.getDate()+DayIncrease); //E.g. First Iteration = Jan 01 + 0 = Jan 01; Second Iteration = Jan 01 + 7 = Jan 08;
NextWeek.setDate(CurrentWeek.getDate()+7); //Should be +7 days from CurrentWeek Value.
var WeekSheetName = Utilities.formatDate(NextWeek,spreadsheet.getSpreadsheetTimeZone(),"MMM DD"); //Should return the date formatted.
Logger.log(WeekNum+" - "+WeekSheetName);
}
}
With Each Iteration, I intend to create WorkSheets with the First Date of each Week Starting from Value of CurrentWeek
Eg: Jan 01, Jan 08, Jan 15, Jan 22, Jan 29, Feb 05, etc...
UPDATE:
I since changed the code to:
function CreateWeekTabs(){
var TotalsSheet = spreadsheet.getSheetByName("Totals");
var CurrentWeek = new Date(TotalsSheet.getRange("B1").getValue()); //Typically always "Jan 01" shown. Cell Formatting is MMM dd. Cell Value is 01/01/2019
// var CurrentWeek = new Date();
var NextWeek = new Date();
spreadsheet.toast("Please wait...","Creating Tabs");
for (var WeekNum = 1;WeekNum <= 12;WeekNum++){
var DayIncrease = (7 * WeekNum) - 7; //Should produce 0,7,14,21,28.... So first iteration won't increase any value from Jan 01.
CurrentWeek.setDate(CurrentWeek.getDate()+DayIncrease); //E.g. First Iteration = Jan 01 + 0 = Jan 01; Second Iteration = Jan 01 + 7 = Jan 08;
NextWeek.setDate(CurrentWeek.getDate()+DayIncrease+7); //Should be +7 days from CurrentWeek Value.
var WeekSheetName = Utilities.formatDate(NextWeek,spreadsheet.getSpreadsheetTimeZone(),"MMM dd"); //Should return the date formatted.
Logger.log("Week Number: "+WeekNum+" - Current Week: "+Utilities.formatDate(CurrentWeek,spreadsheet.getSpreadsheetTimeZone(),"MMM dd")+" Next Week: "+WeekSheetName);
}
}
and the Log is producing the following as outputs. (so I can see what it's producing for Variables 'CurrentWeek' and 'NextWeek'
[19-06-14 14:40:00:463 EDT] Week Number: 1 - Current Week: Jan 01 Next Week: Jun 08
[19-06-14 14:40:00:464 EDT] Week Number: 2 - Current Week: Jan 08 Next Week: Jun 22
[19-06-14 14:40:00:464 EDT] Week Number: 3 - Current Week: Jan 22 Next Week: Jul 13
[19-06-14 14:40:00:465 EDT] Week Number: 4 - Current Week: Feb 12 Next Week: Aug 09
[19-06-14 14:40:00:466 EDT] Week Number: 5 - Current Week: Mar 12 Next Week: Sep 16
[19-06-14 14:40:00:467 EDT] Week Number: 6 - Current Week: Apr 16 Next Week: Oct 28
[19-06-14 14:40:00:468 EDT] Week Number: 7 - Current Week: May 28 Next Week: Dec 16
[19-06-14 14:40:00:468 EDT] Week Number: 8 - Current Week: Jul 16 Next Week: Feb 10
[19-06-14 14:40:00:469 EDT] Week Number: 9 - Current Week: Sep 10 Next Week: Apr 13
[19-06-14 14:40:00:470 EDT] Week Number: 10 - Current Week: Nov 12 Next Week: Jun 21
[19-06-14 14:40:00:471 EDT] Week Number: 11 - Current Week: Jan 21 Next Week: Sep 06
[19-06-14 14:40:00:471 EDT] Week Number: 12 - Current Week: Apr 07 Next Week: Nov 30
Why the blazes? Current Value is calculating correctly, but the value of Next Week is way off, it should be showing +7 days from Current Week.

Answer 1

Try these:
The first calculates the start of week tab name for this week. You can pick the start of week day Sun-Sat is 0-6. The second calculates the start of week tab name for next week.
function thisWeeksStartOfWeekTabname(sow){
var sow=sow || 1;//Sun-0, Sat=6
var ss=SpreadsheetApp.getActive();
var dt=new Date();
while(dt.getDay()>0) {
dt=new Date(dt.setDate(dt.getDate()-1));
}
dt=new Date(dt.setDate(dt.getDate()+sow));
Logger.log(Utilities.formatDate(dt, Session.getScriptTimeZone(), "MMM dd"));
return Utilities.formatDate(dt, Session.getScriptTimeZone(), "MMM dd");
}
function nextWeeksStartOfWeekTabname(sow){
var sow=sow || 1;//Sun-0, Sat=6
var ss=SpreadsheetApp.getActive();
var dt=new Date();
while(dt.getDay()>0) {
dt=new Date(dt.setDate(dt.getDate()+1));
}
dt=new Date(dt.setDate(dt.getDate()+sow));
Logger.log(Utilities.formatDate(dt, Session.getScriptTimeZone(), "MMM dd"));
return Utilities.formatDate(dt, Session.getScriptTimeZone(), "MMM dd");
}