Subtracting dates in javascript

Question

I am working on a Onchange() event form.

By default, the Present Value as of date is today. If a user enters Remaining payments = 12 months then the

End of Lease = Present Value as of date + Remaining payment (i.e months).

For my onchange event i am trying to calculate Start of Lease automatically. Here, Start of Lease = End of lease - Remaining payment.

Here is my code so far. The issue i am having is that the Start of Lease date is getting reflected but it's returning a day less than End of Lease. However, the first part calculating the End of Lease itself is working fine.

function PopulateEndDate() {
debugger;
var d2;
var paymentDays;
var stDate;
var pDate;
var etDate;
var ddlFrequency = document.getElementById("ddFrequency");
var selectedFrequency = ddlFrequency.options[ddlFrequency.selectedIndex].value;

if (document.getElementById("startDate"))
    stDate = document.getElementById("startDate").value;


if (document.getElementById("presentDate"))
    pDate = document.getElementById("presentDate").value;

var today = new Date();

if (stDate)
    d2 = new Date(stDate);
else
    d2 = new Date(pDate);


if (document.getElementById("paymentRemaining")) {
    if (selectedFrequency == "D") {
        paymentDays = document.getElementById("paymentRemaining").value;
    }
    else if (selectedFrequency == "Q") {
        paymentDays = document.getElementById("paymentRemaining").value * 3;
    }
}
if (paymentDays && paymentDays != "")
    d2.setMonth(d2.getMonth() + parseInt(paymentDays));

if (document.getElementById("endDate"))
 document.getElementById("endDate").value = getCurrentDay(d2);
var endDate = document.getElementById("endDate").value;
if (endDate)
    etDate = new Date(endDate);


if (stDate == null && paymentDays && paymentDays != "")
{
    etDate.setMonth(etDate.getMonth() - parseInt(paymentDays));
}

if (document.getElementById("startDate"))
document.getElementById("startDate").value = getCurrentDay(etDate);
}

I am not sure what i am doing wrong here. Any help will be greatly appreciated. Thank you.

Ace1 · Accepted Answer · 2018-05-15 19:59:02Z

1

if (endDate){
var etDate = new Date(endDate);
var eDay = etDate.getUTCDate()+1;
var eMonth = etDate.getUTCMonth()+1;
var eYear = etDate.getUTCFullYear()-1;
var sDate = eYear + "-" + eMonth + "-" + eDay;

    if (stDate == null)
    {
        sDate.setMonth(sDate.getDay() - parseInt(paymentDays));
    }

   if (document.getElementById("startDate"))
        document.getElementById("startDate").value = getCurrentDay(sDate);

This helped solve my problem.

answered May 15, 2018 at 19:59

Ace1

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