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String dates comparison in javascript

So, I have two variables and one function:
function addDays(date, days) {
var result = new Date(date);
result.setDate(result.getDate() + days);
return result;
}
const dateToCompare=moment.utc(endDate).format('DD-MM-YYYY')
const maximum=moment.utc(addDays(new Date(),14)).format('DD-MM-YYYY')
However, I do not know how to compare them, since they are now formatted as strings, but at the same time new Date(dateToCompare) doesn't work.
Can someone give me a hint?

Why are you using built–in methods to add days when you are using moment.js? Consider:
let maximum = moment.utc().add('day',14).format('DD-MM-YYYY')
To set a date to the start of a day, use the moment.js startOf method:
let maximum = moment.utc().add('day',14).startOf('day')
let dateToCompare = moment.utc(endDate).startOf('day')
You can compare the dates as strings if formatted as YYYY-MM-DD, or just leave them as moment objects and compare those using isSame, isAfter, isSameOrBefore, etc.
When parsing strings as in:
const dateToCompare=moment.utc(endDate)
you should always pass the format to parse unless endDate is a Date or moment object. new Date(dateToCompare) doesn't work because Why does Date.parse give incorrect results?

If what you're trying to do is strip out the time and just compare the dates, don't do a string conversion; just set the hour, minutes, and seconds on your Date objects to zero before making your date comparison.
let foo = new Date();
console.log(foo);// date includes time
foo.setHours(0); foo.setMinutes(0); foo.setSeconds(0);
console.log(foo) // date set to midnight (in your timezone)

Issues parsing a string-date React/JS

For example, I have this string "2020-09-09T21:00:14.114-04:00"
I grab this from my database and in its current form, it is a string. my goal is to have it display
4 PM instead of the long string of jibberish
is it possible to accomplish this?
I was thinking of possibly creating a new date object like
let test = new Date('2020-09-09T21:00:14.114-04:00').
but I'm stuck at the parsing and formatting part. it would be better to have this be done while the current state is a string but I don't think that this would be possible
edit: i would like the desired output to be the hour:minute and then am/pm
ex 10:15pm

You can do that by parsing the date from your database using Date.parse().
Then you can get the time or whatever you need using date.toLocalTimeString() in your case.
let dateUnix = Date.parse('2020-09-09T21:00:14.114-04:00');
const time = new Date(dateUnix).toLocaleTimeString();
console.log(time); // --> "4:00:14 AM"
The Date.parse() method parses a string representation of a date, and returns the number of milliseconds since January 1, 1970, 00:00:00 UTC or NaN if the string is unrecognized or, in some cases, contains illegal date values (e.g. 2015-02-31).
Here's some useful resources MDN Date.parse()
MDN Date.toLocalTimeString()

You can do as following way.new Date() is used to get the current date and time.
var today = new Date();
var time = today.getHours();
if(time>12){
var new_time= time % 12;
}
else{
var new_time= time;
}

How to convert into Date time

When the date is passed from my c# to JavaScript it returns the date time as {4/3/2020 12:00:00 AM}
but in JavaScript it is shown as 1585852200000.
What is the format that is being used? And how can i convert it back?

You need to convert the Unix timestamp to DateTime format,
var localDate = new Date(1585852200000).toLocaleDateString("en-US")
console.log(localDate); // only local date
var localTime = new Date(1585852200000).toLocaleTimeString("en-US")
console.log(localTime) // only local time
// local datetime
console.log(new Date(1585852200000).toLocaleString());

1585852200000 is epoch date.
you can convert it as
var date = new Date(1585852200000)
console.log(new Date(1585852200000));

As an alternative from Shivaji's answer:
When you are passing the date through to JS you could cast it as a string with DateTime.ToString("dd/MM/yyyy") seen here on MSDN.
This will keep its integrity visually, if it is just for display purposes, otherwise you will need to re-cast appropriately in JS (in which case use Shivaji's answer).

JavaScript Date's object will return the DATE object and it's POSITION that is being assigned in your computer. So, when you are working with a date or datetime types, you can use some of the methods that are provided by the Date object, such as getDate() and getDay(). But, a better solution would be to format the Date object itself. For example: use the toString() or toUTCString() methods.
var d = new Date();
document.getElementById("demo").innerHTML = d.toString();
Reference:
https://www.w3schools.com/js/js_date_formats.asp
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Date

Comparing a datetime from a get request with the current date time in JavaScript

I need to get the difference (in minutes) from a datetime that I get froma get request in a string format to now.
According to my research, I can use moment.js to do so, but I haven't figured out now.
That format I am getting the date/time to be compared is as:
2017-02-10T20:52:13.885Z
I have already tried to do some operations with moment.js such as
moment().startof(comparedTime).fromNow())
But it returns nothing.
What are the alternatives and the best way to do this?

Can't you just use vanilla javaScript?
var getDate = '2017-02-10T20:52:13.885Z'; //get time from server
var parseDate = new Date(getDate).getTime(); //change string into Date object into milliseconds
var nowDate = Date.now(); //get current Date in milliseconds
var minutes = Math.round((nowDate-parseDate)/1000/60); //subtract times, count seconds (/1000), count minutes (/60)
console.log(minutes);

You need to create a moment object by passing the date string in. e.g.
myDate = moment(myISOString)
https://momentjs.com/docs/#/parsing/
Then you can use the moment object as described in the docs.

With Moment.js, this is simply:
moment().diff('2017-02-10T20:52:13.885Z', 'minutes') // 65
If you want partial minutes included, then pass true as a third parameter:
moment().diff('2017-02-10T20:52:13.885Z', 'minutes', true) // 65.04565

How to do a date format in Javascript?

I need to understand how to do date formattting in javascript.
i have date as,
var date="12/02/1994";// dd/mm/yyy
var date1=new Date(date);
date1.getDate();// this gives me Month which is 02
date1.getMonth();// this gives me date which is 12.
How do i get the exact date i have in var date in get date and getmonth function? Please help

The answer is pretty simple: JavaScript uses mm/dd/yyyy data format.
It doesn't support dd/mm/yyyy format, so, if you need to parse this format, then you will have to do this manually like this:
function parseDdmmyyyy(str)
{
var spl = str.split('/');
return new Date(spl[2], spl[1] - 1, spl[0]);
}
or you will have to use external libraries like Moment.js.

Javascript date() expects date in mm/dd/yy and not in dd/mm/yy. And months start from 0 and not 1.
var from = "12/02/1994".split("/");
var date1 = new Date(from[2], from[1] - 1, from[0]);
date1.getDate();
date1.getMonth();

Use new Date('02/12/1994'), new Date('1994-02-12') or new Date(1994, 02-1, 12), because in js months start from 0 and american date format is used where month goes first

you can use the simple JS file DateFormat.js which has some very good example through the URL mattkruse (Date Funtion)
from this JS file you can validate the incoming date is a true format even you can add format date within a several ways.

Presumably you want to know how to format strings so they are consistently parsed by browsers. The short answer, is there is no guarantee that any particular string will be correctly parsed by all browsers in use (or perhaps even most).
So the bottom line is: don't parse strings with the Date constructor, ever. It's largely implementation dependent and even the one format specified in ES5 and ECMAScript 2015 is poorly and inconsistently supported.
How browsers treat a string like "12/02/1994" is entirely implementation dependent, however most will treat it as the peculiar US month/day/year format, i.e. 2 December and getMonth will return 11, since months are zero indexed.
So you should always manually parse strings (a library can help, but a simple parsing function is only 2 lines, 3 if validation is required), e.g.
// Parse a date string as d/m/y
// If s is not a valid date, return a Date object with its
// time value set to NaN.
function parseDMY(s) {
var b = s.split(/\D/);
var d = new Date(b[2], --b[1], b[0]);
return d && b[1] == d.getMonth()? d : new Date(NaN);
}
document.write(parseDMY('12/02/1994'));