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how get month from a string in javascript

i have a date in string like this: var myDateStr='1431451872338.00';
i want, getMonth() from this format date, i do:var date = new Date(myDateStr); but always return invalid date.
and the method getMont() always return NaN, if I put this: var date = new Date(1431451872338.00); this return the date correct but with my string not
my var myDateStr get the value from json and is variable, if someone can help me thank you very much in advance, i hope do understand

This works fine for me. You just need to be sure you're inputing a number, not a string.
var number = parseInt("1431451872338.00");
var date = new Date(number); //Tue May 12 2015 12:31:12 GMT-0500 (CDT)
var month = date.getMonth(); // 4

A Date object cannot be instantiated with a string. You better 1st transform your string into an Int and then ask for month:
var myDateStr='1431451872338.00';
var date = new Date(parseInt(myDateStr, 10));
alert(date.getMonth());

Could you use parseInt and do something like this:
var myDateStr = '1431451872338.00';
var myDateInt = parseInt(myDateStr, 10);
var myDate = new Date(myDateInt);

When you're passing in a date string to the javascript date object, it needs to be in the format "yyyy/mm/dd" or something like "January 10, 2014". What you're passing is the number of milliseconds since January 1, 1970, which is only accepted by the date object as a number. You need to change the type of your input variable.
Please make sure to research carefully before answering questions - the answer to your question is clearly stated on many date references like this one.

One Liner
var month = date.getMonth(Date(parseInt("1431451872338.00")));

Date to epoch and vice versa - JavaScript

I need to convert date to Java epoch and then read it and convert back. Not sure what I'm doing wrong here?
var date = new Date('1/3/2013');
var timeStamp = date.getTime();
console.log(timeStamp);
var revertDate = new Date(timeStamp);
console.log(revertDate.getDate()+'/'+revertDate.getMonth()+'/'+revertDate.getFullYear());
The output is 3/0/2013 instad 1/3/2013?
fiddle link

You've got two problems here:
The Date constructor is assuming M/d/yyyy format - whereas you're logging d/M/yyyy format. Personally I'd suggest using an ISO-8601 format if at all possible: yyyy-MM-dd
You're not taking into account the fact that getMonth() returns a 0-based value
For the formatting side, you'd be better off using toISOString or something similar, rather than doing the formatting yourself.
(Note that looking at the documentation for the Date constructor it's not clear that the code you've got should work at all, as it's neither an RFC822 nor ISO-8601 format.)
Neither of the problems are to do with converting between Date and a numeric value. If you change your logging, you'll see that clearly:
var date = new Date('1/3/2013');
var timeStamp = date.getTime();
console.log(date);
var revertDate = new Date(timeStamp);
console.log(revertDate);

var date = new Date('1/3/2013');
The Date constructor is parsing this given string this way:
Month / Day / Year
So, in this case, Month is 1, Day is 3 and Year is 2013. What's going on there? Well that's quite simple. This Gregorian representation of a date(which is specifically Day / Month / Year ) isn't the one used by the Date constructor, so it will parse the 1(the month) as January, the 3 as the third day of the month(the third of Jan) and the year correctly, the 2013. Now, due to its 0-based indexing, the constructed Date object will return a month which is n-1 among the one provided. That's why you're getting 3/0/2013. It is the third day(3) of the month 0(which is January) of 2013. If you want to get your real date you have to do this:
var date = new Date('3/1/2013');
console.log(date.getDate()+'/'+(date.getMonth()+1)+'/'+date.getFullYear());

Javascript date string conversion

I have a system that returns a JSON object that contains dates in string format.
These dates are in the format "2012-10-19 06:05:38 GMT" (no... I'm stuck with them like this)
So I need to get this into a date object (d) ready to output as d.toLocaleDateString()
In chrome it works perfectly by just passing the string to a new Date (Bad bad Chrome - makes Eric lazy), but of course it fails in FF and IE
I can fix it by splitting the string but its not pretty and I've not figured out dealing with the offsets from GMT.
There must be a more elegant way...?
I'm sure someone here can do it in one line.

It's not quite a one-liner, but if you know all your dates will be GMT, something like the following should work:
function parseDate(dateString) {
// [y, m, d, hr, min, sec]
var parts = dateString.match(/\d+/g);
// Months are 0-indexed
parts[1] -= 1;
return new Date(Date.UTC.apply(Date, parts));
}

If I were you, and had access to the serverside script gathering that information (and outputting it) I would convert the date into a unix timestamp, and then make Javascript process that using the Date constructor easily.
EDIT: You can use strtotime() function to convert the string date into numeric unix timestamp if you're using PHP.

If you know the exact format, you could use a library such as Moment.js: Documentation for Moment.js.
To parse:
var dateString = "2012-10-19 06:05:38 GMT".replace(" GMT", "");
var date = moment(dateString, "YYYY-MM-DD HH:mm:ss");

You can just parse the dateString manually，and pass the Date the Date constructor exactly：https://developer.mozilla.org/en-US/docs/JavaScript/Reference/Global_Objects/Date
var dateString = "2012-10-19 06:05:38 GMT".split(" "),
date = dateString[0].split("-"),
time = dateString[1].split(":");
var dateObj = new Date(date[0],date[1]-1,date[2],time[0],time[1],time[2]);

Issue with javascript date object

I am facing a weird problem while initializes javascript date object,no matter what I initialize to it shows the date as 1 JAN 1970 05:30;
this is the way I try to initialize
var d=new date(27-02-1989);
alerting 'd' shows 1 JAN 1970.....,also sometimes it takes a date passed from the database but in the format as mm/dd/yyyy not in the format I want i.e dd/mm/yyyy
This problem has suddenly popped-up, as everything was working smooth couple of days ago,but today after opening the project (after 2 days) this issue is irritating me

I see you've accepted an answer, but it isn't the best you can do. There is no one format that is parsed correctly by all browsers in common use, the accepted answer will fail in IE 8 at least.
The only safe way to convert a string to a date is to parse it, e.g.
var s = '27-02-1989';
var bits = s.split('-');
var date = new Date(bits[2], --bits[1], bits[0]);

// Transform your european date in RFC compliant date (american)
var date = '27-02-1989'.split('-').reverse().join('-');
// And this works
var d = new Date( date );
Proof:

You're doing an initialization with a negative integer value (27-02-1989 == -1964). The Date object's constructor takes arguments listed here.
If you want to pass strings, they need to be in an RFC2822-compliant format (see here).

according to here you can try:
new Date()
new Date(milliseconds)
new Date(dateString)
new Date(year, month, day [, hour, minute, second, millisecond ])
so for your case use (edit: You need to remember that months are zero based)
var d = new Date(1989,01,27);
pleas notice - use Date (capital D)

First of all
var d=new date(27-02-1989);
is totaly wrong expression in javascript, moreover even if we rewrites it more correctly:
var d=new Date('27-02-1989');
there is no way to parse this date string natively in js.
Here solutions you can try:
transform string to ISO8601: YYYY-mm-dd, this can be parsed by most modern broswers, or you can use many js libraries for polyfill
split string string by '-' and then use Date constructor function new Date(year, month-1, day)
split string and use setDate, setMonth, setYear method on new Date() object
Note that in last two methods you need to deduct 1 from month value, because month is zero-based (0 stands for January, 11 for December)

Jquery Date.parse returning NaN in Chrome browser?

I have a senario where i have to parse two dates for example start date and end date.
var startdate = '02/01/2011';
var enddate = '31/12/2011';
But if we alert start date
alert(Date.Parse(startdate)); i will get 1296498600000
but if i alert enddate
alert(Date.Parse(enddate)); i will get NaN
But this is working in other browsers except Chrome, But in other browsers
alert(Date.Parse(enddate)); i will get 1370889000000
Can anybody know a workaround for this?

If you want to parse a date without local differences, use the following, instead of Date.parse():
var enddate = '31/12/2011'; //DD/MM/YYYY
var split = enddate.split('/');
// Month is zero-indexed so subtract one from the month inside the constructor
var date = new Date(split[2], split[1] - 1, split[0]); //Y M D
var timestamp = date.getTime();
See also: Date

According to this
dateString
A string representing an RFC822 or ISO 8601 date.
I've tried your code and I also get NaN for the end date, but if i swap the date and month around, it works fine.