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JavaScript or Jquery - How to display last week of the month and next month's first Monday

How do you display only when it's the last week of the month (the text below).
The DATE that will be displayed here is next month's first Monday.
"Due on DD/MM/YY"

To detect if this is the last week in month you can follow this example:
https://www.javatpoint.com/calculate-current-week-number-in-javascript
To get next monday, you can call this function:
getNextMonday(){
var date = new Date();
date.setDate(date.getDate() + (1 + 7 - date.getDay()) % 7);
return date;
}

You can use the below JS Code. It will show the alert on last week of month means from last monday of month.
function Get_Last_Monday_of_Month()
{
var year = new Date().getFullYear();
var month = new Date().getMonth() + 1;
var dat = new Date(year+'/'+month+'/1');
var currentmonth = month;
var firstmonday = false;
while (currentmonth === month)
{
firstmonday = dat.getDay() === 1 || firstmonday;
dat.setDate(dat.getDate()+(firstmonday ? 7 : 1));
currentmonth = dat.getMonth()+1;
}
dat.setDate(dat.getDate()-7);
return dat;
}
function Get_Next_Coming_Monday()
{
var date = new Date();
date.setDate(date.getDate() + (1 + 7 - date.getDay()) % 7);
return date;
}
var d1 = new Date();
var d2 = Get_Last_Monday_of_Month();
var d3 = Get_Next_Coming_Monday();
if (d1.getTime() >= d2.getTime())
{
var datestring = ("0" + d3.getDate()).slice(-2) + "/" + ("0"+(d3.getMonth()+1)).slice(-2) + "/" + d3.getFullYear();
document.write ("Due on " + datestring);
}

how to Add 1 year to startdate to get the end date in javascript

want a output like below
if Start Date is "01-03-2016" the End date should be "28-02-2017"
if Start Date is "10-04-2016" the End date should be "09-04-2017"
I tried below code
if (dat <= 31 && dat >= 1 && month <= 12 && month >= 1) {
var expiryDate = new Date(n1, month - 1, dat);
expiryDate.setFullYear(expiryDate.getFullYear() + 1);
var day = ('0' + expiryDate.getDate()).slice(-2);
var month1 = ('0' + (expiryDate.getMonth() + 1)).slice(-2);
var year = expiryDate.getFullYear();
var month = getMonthName(month1);
var wholeenddate = day + "-" + month + "-" + year;
but it's not produce desired output.Please Help to solve it.

Add 364 days to your date
For example
var d = new Date("2016-03-01");
d.setDate(d.getDate()+364); //outputs 28-02-2017
and
var d = new Date("2016-04-10");
d.setDate(d.getDate()+364); //outputs 09-04-2017
or Just add 1 year and sub 1 day.
d.setFullYear(d.getFullYear() + 1);
d.setDate(d.getDate()-1);
Now it will match your output just the same even for leap year :)
Demo
var d = new Date("2016-03-01");
d.setFullYear(d.getFullYear() + 1);
d.setDate(d.getDate()-1);
document.body.innerHTML += d.toString();
document.body.innerHTML += "<br>";
d = new Date("2016-04-10");
d.setFullYear(d.getFullYear() + 1);
d.setDate(d.getDate()-1);
document.body.innerHTML += d.toString();

There's a convenient library to help with this sort of thing - moment.js (14k zipped).
var startDate = moment('01-03-2016', 'DD-MM-YYYY');
console.log(startDate.format('DD-MM-YYYY'));
var endDate = startDate.clone();
endDate.add(1, 'years').subtract('1', 'days');
console.log(endDate.format('DD-MM-YYYY'));

3 ways to do this.
// Add hours
var today = new Date();
today.setHours(today.getHours()+24*364);
// Add days
var nextyearDate = new Date();
nextyearDate.setDate(today.getDate()+364);
// More reliable way : Add year & subtract a day.. Hope this works...! Works for 01/01/2016
var nextDate = new Date();
nextDate.setYear(nextDate.getFullYear()+1);
nextDate.setDate(nextDate.getDate()-1);

javascript date of specific day of the week in MM/dd/yyyy format not libraries

I know there are a lot of threads about finding the date of a specific day of the week in javascript but the all give it in the format like so:
Sun Dec 22 2013 16:39:49 GMT-0500 (EST)
but I would like it in this format 12/22/2013 -- MM/dd/yyyy
Also I want the most recent Sunday and the code I have been using does not work all the time. I think during the start of a new month it screws up.
function getMonday(d) {
d = new Date(d);
var day = d.getDay(),
diff = d.getDate() - day + (day == 0 ? -6:0); // adjust when day is sunday
return new Date(d.setDate(diff));
}
I have code that gives me the correct format but that is of the current date:
var currentTime = new Date()
var month = currentTime.getMonth() + 1
var day = currentTime.getDate()
var year = currentTime.getFullYear()
document.write(month + "/" + day + "/" + year)
this prints:
>>> 12/23/2013
when I try to subtract numbers from the day it does not work, so I cannot get the dat of the most recent Sunday as MM/dd/yyyy
How do I get the date of the most recent sunday in MM/dd/yyyy to print, without using special libraries?

You can get the current weekday with .getDay, which returns a number between 0 (Sunday) and 6 (Saturday). So all you have to do is subtract that number from the date:
currentTime.setDate(currentTime.getDate() - currentTime.getDay());
Complete example:
var currentTime = new Date()
currentTime.setDate(currentTime.getDate() - currentTime.getDay());
var month = currentTime.getMonth() + 1
var day = currentTime.getDate()
var year = currentTime.getFullYear()
console.log(month + "/" + day + "/" + year)
// 12/22/2013
To set the date to any other previous weekday, you have to compute the number of days to subtract explicitly:
function setToPreviousWeekday(date, weekday) {
var current_weekday = date.getDay();
// >= always gives you the previous day of the week
// > gives you the previous day of the week unless the current is that day
if (current_weekday >= weekday) {
current_weekday += 6;
}
date.setDate(date.getDate() - (current_weekday - weekday));
}
To get the date of next Sunday you have to compute the number of days to the next Sunday, which is 7 - currentTime.getDay(). So the code becomes:
currentTime.setDate(currentTime.getDate() + (7 - currentTime.getDay()));

Subtract days like this
// calculate days to subtract as per your need
var dateOffset = (24*60*60*1000) * 5; //5 days
var date = new Date();
date.setTime(date.getTime() - dateOffset);
var day = date.getDate() // prints 19
var month = date.getMonth() + 1
var year = date.getFullYear()
document.write(month + '/' + day + '/' + year);

Here is my suggestion. Create a function like so... in order to format any date you send it.
function formatDate(myDate) {
var tmp = myDate;
var month = tmp.getMonth() + 1;
var day = tmp.getDate();
var year = tmp.getFullYear();
return (month + "/" + day + "/" + year);
}
Now, to print the current date, you can use this code here:
var today = new Date();
var todayFormatted = formatDate(today);
To get the previous Sunday, you can use a while loop to subtract a day until you hit a Sunday, like this...
var prevSunday = today;
while (prevSunday.getDay() !== 0) {
prevSunday.setDate(prevSunday.getDate()-1);
}
var sundayFormatted = formatDate(prevSunday);
To see the whole thing together, take a look at this DEMO I've created...
** Note: Make sure you turn on the Console tab when viewing the demo. This way you can see the output.

You can create prototype functions on Date to do what you want:
Date.prototype.addDays = function (days) {
var d = new Date(this.valueOf());
d.setDate(d.getDate() + days);
return d;
}
Date.prototype.getMostRecentPastSunday = function () {
var d = new Date(this.valueOf());
return d.addDays(-d.getDay()); //Sunday is zero
}
Date.prototype.formatDate = function () {
var d = new Date(this.valueOf());
//format as you see fit
//http://www.webdevelopersnotes.com/tips/html/10_ways_to_format_time_and_date_using_javascript.php3
//using your approach...
var month = d.getMonth() + 1
var day = d.getDate()
var year = d.getFullYear()
return month + "/" + day + "/" + year;
}
console.log((new Date()).getMostRecentPastSunday().formatDate());
console.log((new Date("1/3/2014")).getMostRecentPastSunday().formatDate());
//or...
var d = new Date(); //whatever date you want...
console.log(d.getMostRecentPastSunday().formatDate());

Something like this will work. This creates a reusable dateHelper object (you will presumably be adding date helper methods since you don't want to use a library off the shelf). Takes in a date, validates that it is a date object, then calculates the previous Sunday by subtracting the number of millis between now and the previous Sunday.
The logging at the bottom shows you how this works for 100 days into the future.
var dateHelper = {
getPreviousSunday: function (date) {
var millisInADay = 86400000;
if (!date.getDate()) {
console.log("not a date: " + date);
return null;
}
date.setMilliseconds(date.getMilliseconds() - date.getDay() * millisInADay);
return date.getMonth() + 1 + "/" + date.getDate() + "/" + date.getFullYear();
}
}
var newDate = new Date();
console.log(dateHelper.getPreviousSunday(newDate));
var now = newDate.getTime();
for (var i=1; i<100; i++) {
var nextDate = new Date(now + i * 86400000);
console.log("Date: + " nextDate + " - previous sunday: " + dateHelper.getPreviousSunday(nextDate));
}

validate a dropdown list to get proper date based on the option selected

- I have a dropdown List on which there are some options from which user can select one.
- Options are 1 day, 1 week, 2 weeks, 1 month and 6 months
- Now when I select option 1 day, today's date should be incremented by one and next date is shown.
- If I select 1 week, the date falling after one week should be shown.
- Now the problem is when I select an option it sometimes shows date greater than 30/31.
- I use below javacript function:
function select_duration(ddlcupon) {
var skillsSelect = document.getElementById("ddlcupon");
var selectedText = skillsSelect.options[skillsSelect.selectedIndex].text;
if (selectedText == "1 Day") {
var currentTime = new Date();
var month = currentTime.getMonth() + 1;
var day = currentTime.getDate() + 1;
var year = currentTime.getFullYear();
var exdate = month + "/" + day + "/" + year;
document.getElementById('<%=txtEventDate.ClientID%>').value = exdate.toString();
}
if (selectedText == "1 Week") {
var currentTime = new Date();
var month = currentTime.getMonth() + 1;
var day = currentTime.getDate() + 7;
var year = currentTime.getFullYear();
var exdate = month + "/" + day + "/" + year;
document.getElementById('<%=txtEventDate.ClientID%>').value = exdate.toString();
}
if (selectedText == "2 Weeks") {
var currentTime = new Date();
var month = currentTime.getMonth() + 1;
var day = currentTime.getDate() + 14;
var year = currentTime.getFullYear();
var exdate = month + "/" + day + "/" + year;
document.getElementById('<%=txtEventDate.ClientID%>').value = exdate.toString();
}
if (selectedText == "1 Month") {
var currentTime = new Date();
var month = currentTime.getMonth() + 2;
var day = currentTime.getDate();
var year = currentTime.getFullYear();
var exdate = month + "/" + day + "/" + year;
document.getElementById('<%=txtEventDate.ClientID%>').value = exdate.toString();
}
if (selectedText == "6 Months") {
var currentTime = new Date();
var month = currentTime.getMonth() + 7;
var day = currentTime.getDate();
var year = currentTime.getFullYear();
var exdate = month + "/" + day + "/" + year;
document.getElementById('<%=txtEventDate.ClientID%>').value = exdate.toString();
}
- Can someone help me in getting a proper date?

try using this
var dt1 = new Date();
var dt2 = new Date(dt1.getTime() + (86400000 * numberOfDay) );
if your date is incremented by one day try
var dt2 = new Date(dt1.getTime() + (86400000 * 1 ) ); //so on

The problem is you're incrementing day, month and year. So, if the month is 12, you'll get 13. You could work directly with milliseconds. For example:
var d = new Date('01/31/2013'); // Thu Jan 31 2013 00:00:00 GMT-0200 (BRST)
var addDay = 1000 * 60 * 60 * 24;
var currentMs = d.getTime();
d.setTime(currentMs + addDay);
console.log(d); // Fri Feb 01 2013 00:00:00 GMT-0200 (BRST)

Date.js is a handy script for all kinds of JavaScript date manipulation.
The syntax to add n number of days to current day is
// Add 3 days to Today
Date.today().add(3).days();
In this case adds 3 days to the current date.

Calculate days of the week from Monday to Saturday

In my form I have a datafield where I select the day of the week!
For example if I select today 23-03-2012 Friday, I need to get an array of days from previous Monday to this next Saturday.
array:
[0],[19-03-2012],[Monday]
[1],[20-03-2012],[Monday]
[2],[21-03-2012],[Wednesday]
[3],[22-03-2012],[Monday]
[4],[23-03-2012],[Friday]
[5],[24-03-2012],[Saturday]
How can i do it for any selected day of the week obviously paying attention to changes?
Thanks

This function will return an array of all the dates in the week of date, Monday to Saturday.
function GetDaysOfWeek(date)
{
var days = new Array();
for (var i = 0; i < 6; i++)
{
days[i] = new Date(date.getYear(),
date.getMonth(),
date.getDate() - date.getDay() + 1 + i);
}
return days;
}

mayby try out MomentJs: http://momentjs.com/docs/
some examples:
moment().day(-7); // set to last Sunday (0 - 7)
moment().day(7); // set to next Sunday (0 + 7)
moment().day(10); // set to next Wednesday (3 + 7)
moment().day(24); // set to 3 Wednesdays from now (3 + 7 + 7 + 7)

For display the current day of the week:
var now = new Date();
var dayNames = ["Sunday","Monday","Tuesday","Wednesday","Thursday","Friday","Saturday"];
document.write("Today is " + dayNames[now.getDay()] + ".");

First find todays date
Find the last monday (including today)
Show that date, and the next 5 days after it (Tuesday-Saturday)
var d = new Date();
if (d.getDay()==0){
d.setDate(d.getDate() + 1);
}
​while (d.getDay() != 1){
d.setDate(d.getDate() - 1);
}
var days = new Array();
for (var i = 0; i < 6; i++){
days[i] = d.getDate() + i;
}
return days;

try this :
var dayString = ["Sunday","Monday","Tuesday","Wednesday","Thursday","Friday","Saturday"];
var now = new Date();
var currentDay = now.getDay(); // return 0 for Sunday, 6 for Saturday
var result = [];
var tempDate = new Date(now.getTime());
tempDate.setDate(now.getDate()-(currentDay+6)%7); // now tempDate is previous Monday
while(tempDate.getDay()!=0) {
var currentMonth = tempDate.getMonth()+1;
if(currentMonth<10) currentMonth = "0"+currentMonth;
result.push([tempDate.getDay()-1,tempDate.getDate()+"-"+currentMonth+"-"+tempDate.getFullYear(),dayString[tempDate.getDay()]]);
tempDate.setDate(tempDate.getDate()+1);
}
console.log(result);

Something like the following will do the trick, I"m sure you can get the formatting to where you want it.
// Assuming d is a date object
function getDateArray(din) {
// Add leading zero to one digit numbers
function aZ(n){return (n<10? '0':'') + n;}
var days = ['Sunday','Monday','Tuesday','Wednesday',
'Thursday','Friday','Saturday'];
var d = new Date(din); // Don't wreck input date
var dn = d.getDay();
var a = [];
var i = 6; // length of day array
if (!dn) {
// It's Sunday, what now?
return ['Sunday!'];
}
d.setDate(d.getDate() + 6 - dn); // Next Saturday
do {
a[i--] = i + ' ' + aZ(d.getDate()) +
'-' + aZ(d.getMonth() + 1) +
'-' + d.getFullYear() +
' ' + days[d.getDay()];
d.setDate(d.getDate() - 1);
} while (i);
return a;
}
// Test it
var date = new Date(2012,2,2)
alert( date + '\n\n' + getDateArray(date).join('\n'));
/*
Fri Mar 02 2012 00:00:00
0 27-02-2012 Monday
1 28-02-2012 Tuesday
2 29-02-2012 Wednesday
3 01-03-2012 Thursday
4 02-03-2012 Friday
5 03-03-2012 Saturday
*/