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Add time to string data/time

I am trying to pass a time stamp to my API that comes in the format of YYYY-MM-DD HH:MM:SS but i need to manipulate the time to add 5 hours.
Have I done something wrong here? Do I need to convert it to a JavaScript date first?
var manDate = "2020-08-16 16:15:00"
manDate.setHours(manDate.getHours() + 5);
data.manDate = manDate
console.log(manDate)
Expected output - 2020-08-16 21:15:00

When you create a var for date, you need to add the 'new Date()' method.
var manDate = new Date("2020-08-16 16:15:00");
manDate.setHours(manDate.getHours() + 5);
console.log(manDate.getHours());
And to log the hours use getHour() again in the log statement.

Use simpleDateFormat to format the date, then cast the formatted date to calendar and add hours to it.
Try with below code.
SimpleDateFormat sdfObj = new SimpleDateFormat("yyyy.MM.dd HH:mm:ss");
sdfObj.parse("2020-08-16 16:15:00");
Calendar calendar = sdfObj.getCalendar();
calendar.add(Calendar.HOUR_OF_DAY, 5);

The question was asked to give a solution in java earlier. Below is the answer as per java.
Date newDate = DateUtils.addHours(oldDate, 5);

how to get date and time together in javaScript

Is there a way to get date and time in JS?
I searched in google and saw ways to get the date appart and time appart but not together.
I have a field that calls "Date Time" and i need to show data -12 hours so i need to figure out how to save datetime.
Can someone help?

Use javaScript Date object to work with date and time.
alert(new Date());

Use new Date();
var x = new Date();
You can also fetch each value using .getDay() , .getMonth(), .getYear(), .getHours(), .getMinutes(), .getSeconds()
Like
x.getHours(); // Will give you hours.

use date object of javascript then adjust your date and time combinations
for example, create a function getdateTime which will return dateTime combinations
function getdateTime() {
var date = new Date();
var dataVal=date.getDate() +"/"+ (date.getMonth() + 1)+"/" + date.getFullYear() + ":" + date.getHours() + ":" + date.getMinutes();
return dataVal;
}
var datetime=getdateTime();
console.log("datetime:" +datetime);
output for example : datetime:18/2/2015:14:26
ie current date and time
since months starts from 0 to 11 you have to add 1 to get current month.
you can use other date functions depending upon your requirements.

why javascript's .getTime() + 24*60*60*1000 get's stack after 27 Oct 2013?

I was just creating a simple calendar when users clicks next it gets the following day, very simple code:
var dateSelected = new Date('02/06/2013'); //any date
var day = new Date(dateSelected.getTime() + 24*60*60*1000);
alert(day.getDate());
that works great for all dates but for some reason it doesn't get the next day when the date is 27 Oct 2013
var dateSelected = new Date('10/27/2013');
I don't seem to be able to figure out why, if I go manually to the next day 28 Oct it keeps working fine.
Any ideas why this happens?
UPDATE:
I fixed it by adding the time as well as the date:
var dateSelected = new Date('10/27/2013 12:00:00');

I strongly suspect this is because of your time zone - which we don't know, unfortunately.
On October 27th 2013, many time zones "fall back" an hour - which means the day is effectively 25 hours long. Thus, adding 24 hours to your original value doesn't change day if it started within the first hour of the day.
Fundamentally, you need to work out whether you're actually trying to add a day or add 24 hours - they're not the same thing. You also need to work out which time zone you're interested in. Unfortunately I don't know much about Javascripts date/time API, but this is almost certainly the cause of the problem.

Rather than adding the number of milliseconds in a day, you can use the set date function directly.
var dateSelected = new Date('10/27/2013');
var daysToAdd = 1;
var nextDay = new Date(dateSelected.getTime());
nextDay.setDate(dateSelected.getDate() + daysToAdd);
This also works when rolling over to the next month, and should work well with different time zones.

As Jon Skeet already mentioned, the problem results from your local timezone. As a possible solution, you can use the setDate and getDate functions of the Date object:
var dateSelected = new Date('02/06/2013'); //any date
dateSelected.setDate(dateSelected.getDate() + 1);
alert(dateSelected.getDate());

And of course, no JavaScript Date question could be complete without a Moment.js answer:
var m = moment('10/27/2013','MM/DD/YYYY').add('days', 1);
Superior API every time. :-)

how to get current date in the below format using jquery

how to display the date in this below format using jQuery.
Thursday, January 08, 2013
I saw some plugins but wondering if there is a way without using any plugin.
Please advise if there is a straightforward answer using JavaScript, that's fine too.

The simplest answer is to use:
date.toLocaleDateString()
But, it will use the locale defined by the user's system. The American/English locale fitting your desired output. (I'm not sure about other locales and how they format dates).
So, if you want the date string to always be in that format, this will not be the best answer for you. But, if you want the date to match the user's locale, this answer is the simplest and most correct. :)
http://jsfiddle.net/SyjpS/
var date = new Date();
console.log(date.toLocaleDateString()); // Tuesday, January 08, 2013 (on my machine)
EDIT — If you're asking how to change the calendar so that today is Thursday instead of Tuesday, you may need to talk to Caesar about adjusting the calendar realignment. For this, you'll need a time machine. I suggest that you seek out the Doctor, but he may not be willing to change history willy nilly.

Here's a quick/simple example of what you're asking for:
EDIT - I've update the code for reuse and include the day 0 padding change.
var d = new Date();
console.log(formatDate(d));
function formatDate(d){
var months = ["Januaray", "February", "March"]; //you would need to include the rest
var days = ["Sunday", "Monday", "Tuesday"];//you would need to include the rest
return days[d.getDay()] + ", " + months[d.getMonth()] + " " + (d.getDate() < 10 ? "0" + d.getDate() : d.getDate()) + ", " + d.getFullYear();
}
Output for today: Tuesday, Januaray 08, 2013
EXAMPLE

Simply use DateJS not to reinvent the wheel.
You may read the API documentation here:
http://code.google.com/p/datejs/wiki/APIDocumentation

The date methods allow you to retrieve all of the different parts of the date and time as numerical values. In the case of the month of the year and the day of the week, the number that is provided is one less than you would normally expect. The reason for this is that the most common use for these values is to use it to look up the name of the month or day from an array and as arrays in JavaScript are numbered from zero, providing the numbers like that reduces the amount of code needed to do the name lookups.
We can go one better than just doing this lookup using the retrieved values though. What we can do is to add extra methods to the Date object to allow us to retrieve the month and day names whenever we want the exact same way that we retrieve any of the other information about the date.
The probable reason why the following methods are not built into the JavaScript language itself is that they are language dependent and need to have different values substituted into the code depending on the language that you want to display the month and day in. For the purpose of showing you how to code this I am going to use the Emglish names for the months and days. If you want to display dates in a different language you will need to substitute the names from that language for their English equivalents.
What we are going to do is to add getMonthName() and getDayName() methods to all our dates so that we can get the month name or day name by calling these new methods directly instead of having to call getMonth() or getDay() and then do an array lookup of the corresponding name. What we are actually doing is building the required array lookups into the new methods so that we can automatically get the correct names for any of our date objects simply by calling the appropriate method.
We don't neeed all that much code to do this. All you need to do to add the getMonthName() and getDayName() methods to all of the date objects that you use is to add the following short piece of code to the very top of the javaScript code attached to the head of your page. Any subsequent processing of date objects will then be able to use these methods.
Date.prototype.getMonthName = function() {
var m = ['January','February','March','April','May','June','July',
'August','September','October','November','December'];
return m[this.getMonth()];
}
Date.prototype.getDayName = function() {
var d = ['Sunday','Monday','Tuesday','Wednesday',
'Thursday','Friday','Saturday'];
return d[this.getDay()];
}
So now with that in place we can display today's date on the page using those new methods in addition to the existing ones. For example we might use the following to get the full date and display it using an alert:
var today = new Date;
alert((today.getDayName() + ', ' + today.getDate() + ' ' + today.getMonthName() + ', ' + today.getFullYear());
Alternatively, we can just retrieve the current month June and day of the week Sunday and use them however we want just the same as for any of the other parts of the date.
function disp() {
var today = new Date;
document.getElementById('mth').innerHTML = today.getMonthName();
document.getElementById('dow').innerHTML = today.getDayName();
}

Comparing today's date with another date in moment is returning the wrong date, why?

I'm using moment.js 1.7.0 to try and compare today's date with another date but the diff function is saying they are 1 day apart for some reason.
code:
var releaseDate = moment("2012-09-25");
var now = moment(); //Today is 2012-09-25, same as releaseDate
console.log("RELEASE: " + releaseDate.format("YYYY-MM-DD"));
console.log("NOW: " + now.format("YYYY-MM-DD"));
console.log("DIFF: " + now.diff(releaseDate, 'days'));
console:
RELEASE: 2012-09-25
NOW: 2012-09-25
DIFF: 1
Ideas?

Based on the documentation (and brief testing), moment.js creates wrappers around date objects. The statement:
var now = moment();
creates a "moment" object that at its heart has a new Date object created as if by new Date(), so hours, minutes and seconds will be set to the current time.
The statement:
var releaseDate = moment("2012-09-25");
creates a moment object that at its heart has a new Date object created as if by new Date(2012, 8, 25) where the hours, minutes and seconds will all be set to zero for the local time zone.
moment.diff returns a value based on a the rounded difference in ms between the two dates. To see the full value, pass true as the third parameter:
now.diff(releaseDate, 'days', true)
------------------------------^
So it will depend on the time of day when the code is run and the local time zone whether now.diff(releaseDate, 'days') is zero or one, even when run on the same local date.
If you want to compare just dates, then use:
var now = moment().startOf('day');
which will set the time to 00:00:00 in the local time zone.

RobG's answer is correct for the question, so this answer is just for those searching how to compare dates in momentjs.
I attempted to use startOf('day') like mentioned above:
var compare = moment(dateA).startOf('day') === moment(dateB).startOf('day');
This did not work for me.
I had to use isSame:
var compare = moment(dateA).isSame(dateB, 'day');