Google spreadsheet function

JavaScript
1 
function endofmonth(input) {

var daysDays0 = 28;
var daysDays1 = 29;
var daysDays2 = 30;
var daysDays3 = 31;



 
var str = "11-12-1959";
var res = str.split(" ");

//prompt("str");
//alert("str");


dDate = res[0];
mMonth = res[1];
yYear = res[2] + 60;

mathsdDate = dDate;
mathsmMonth = mMonth;
mathsyYear = yYear;

leapyearornot = "no"

leapyear = mathsyYear % 400;

if (leapyear == 0) {
 leapyearornot = "yes"
} else { 
 leapyear = mathsyYear % 100
}


if (leapyear == 0) {
 leapyearornot = "yes"
} else { 
 leapyear = mathsyYear % 4
}

if (leapyear == 0) {
 leapyearornot = "yes"
} else { 
// 
}


if (mathsdDate == 1) {
 lastmonthornot = "yes"
} else { 
// 
}

if (mathsdDate > 1) {
 lastmonthornot = "no"
} else { 
// 
}


resultYear = mathsyYear;



if(mathsdDate == 1 && mathsmMonth == 1){
  resultYear = mathsyYear - 1;
}

resultMonth = mathsmMonth


if ( mathsdDate == 1 ); {
  resultMonth = mathsmMonth - 1
}

if ( resultMonth == 0 ); {
resultMonth = 12
}


if ( resultMonth == 1 || resultMonth == 3 || resultMonth == 5 || resultMonth == 7 || resultMonth == 8 || resultMonth == 10 || resultMonth == 12 ); {
resultDate = "31"
}

if ( resultMonth == 4 || resultMonth == 6 || resultMonth == 9 || resultMonth == 11 ); {
resultDate = "30"
}

if ( resultMonth == 2 && leapyearornot == "yes" ); {
resultDate = "29"
}

if ( resultMonth == 2 && leapyearornot == "no" ); {
resultDate = "28"
}



if ( resultMonth < 10 ) ; {
endofmonth = resultDate + "-0" + resultMonth + "-" + resultYear
}


if ( resultMonth > 9 ) ; {
endofmonth = resultDate & "-" & resultMonth & "-" & resultYear
}
return endofmonth;
}

Could someone please look into this code.
Thanks.

3

Thanks.

  1. Add 60 years to year.
  2. I want to get the last date of the current month entered in the initial few lines.
    If that date happen to be 1-1-XXXX
    I want it to be last 31-12-(xxxx-1)

Eg : 3-1-1959
Add 60 to 1959 = 2019
result :

31-12-209