google script type error is not a function in date function - date

Question

can someone help me figure what's wrong with my logic?, i'm new using google script app and stuck around a week and got this error
Error message:
TypeError: d1.getTime is not a function (inDays)
var DateDiff = {
inDays: function(d1, d2) {
var t2 = d2.getTime();
var t1 = d1.getTime();
Logger.log("t1" + t1)
return parseInt((t2-t1)/(24*3600*1000)+1);
}
}
var dateStr = data[m][xMonth].toString() // the value here is =>1/10/2022
var todayDate = new Date();
if(dateStr.toString().includes('/')){
var yearA = '20'+dateStr.substring(6, 8)
var monthA = +dateStr.substring(3, 5)
if(monthA.toString() != '11' || monthA.toString() != '12') monthA = '0'+monthA
var dayA = +dateStr.substring(0, 2)
var tempDate = yearA + monthA + dayA
var Ryear = +tempDate.substring(0, 4)
var Rmonth = +tempDate.substring(4, 6)
var Rday = +tempDate.substring(6, 8)
var newDate = new Date(Ryear, Rmonth - 1, Rday)//because month start from 0
var realDueDate = DateDiff.inDays(todayDate, newDate) // error here in var newDate
}

Answer 1

Try this:
function myFunk() {
const D2 = new Date();
const D1 = new Date(D2.getFullYear(),D2.getMonth() - 2,D2.getDate());
var DateDiff = {
d1:D1,d2:D2,
inDays: function () {
let t2 = this.d2.getTime();
let t1 = this.d1.getTime();
return parseInt((t2 - t1) / (24 * 3600 * 1000) + 1);
}
}
Logger.log(DateDiff.inDays());
}
Execution log
10:58:41 AM Notice Execution started
10:58:39 AM Info 62.0
10:58:41 AM Notice Execution completed