Develop Reference

Getting timezone label in JavaScript

I know JavaScript Date objects contain getTimezoneOffset() for getting the offset, but is there any method that returns the label or name for that timezone?
For example, on my computer, in Chrome's console, if I do:
> new Date().toString();
Then I get:
< "Thu Feb 25 2016 08:49:56 GMT-0800 (Pacific Standard Time)"
What I'd like to do is take a Date and get back "Pacific Standard Time" portion for it.
Is this possible, and if so, how?

I dont think there is a reliable way without regex matching (see #nils answer). Not sure what caveats that date string comes with, so might be fragile? It looks like there are some libraries available that can simplify this
https://bitbucket.org/pellepim/jstimezonedetect/wiki/Home
var timezone = jstz.determine();
timezone.name();
"Europe/Berlin"

There's no straight forward way. You can get it through the following method.
Alternatively you can choose REGEX.
function getTimeZoneLabel(){
var str = new Date().toString();
return str.substring(str.indexOf("(")+1,str.indexOf(")"));
}

You could use a regular expression to get it:
var d = new Date().toString();
var timezone = d.match(/\(([^)]+)\)/)[1];

An approach would be to just get what's inside the paranteses. Juan Mendes posted a solution:
function getTimeZone() {
return /\((.*)\)/.exec(new Date().toString())[1];
}
getTimeZone();
Note that this is language, OS and browser specific (and therefor of course not the ideal solution).
If it is however okay for you to use a library, you could use jsTimezoneDetect.

How to get browser time zone in JavaScript

Is it possible to get the user time zone in JavaSript in tz database format e.g. America/Los Angeles?
I noticed that when I create a Date object its toString method returns something like this:
Thu May 08 2014 08:40:48 GMT-0700 (Pacific Standard Time)
so maybe it's possible to change it to one of ids in tz database from this region (unfortunately chrome shows Pacific Daylight Time so it seems like there's no standard format to display). I need some library because I don't have time to right it myself with all possible combination and discrepancies in browsers like firefox vs chrome.

Best answer I found so far
var d = new Date()
var gmtHours = -d.getTimezoneOffset()/60;
console.log("The local time zone is: GMT " + gmtHours);

From: http://www.w3schools.com/jsref/jsref_gettimezoneoffset.asp
Return the timezone difference between UTC and Local Time:
var d = new Date()
var n = d.getTimezoneOffset();
The result n will be 420. Divide that by 60 to difference in hours.
You could then create an array populated text so that:
timezoneArray[n] = "tz text description";

How do I append the user's timezone to a string in Javascript?

I found some code here on Stack Overflow that does exactly what I want, which is to take a GMT time string and convert it to the local time on the user's browser. Awesome.
However, I'm stuck on what should be a very small thing. When I display the time, I want the user's current local timezone to display along with the time. The goal is to output a string that looks something like:
2014/02/19 15:12 (PST)
I've looked at the parameters for the Javascript Date() function, but, unless I'm blind, I don't see one that outputs the user's timezone. There's getTimezoneOffset(), which returns a number, but not the code for the timezone.
I've got all the rest of the time displaying fine, except for that last part where I want it to say PST (or GMT or JST or wherever the user is). Is there a way to do that?

It can be done creating a date and then performing some operations on it. If you take a look at format in which newly created Date object is created it is e.g. like:
Wed Feb 19 2014 07:29:26 GMT+0100 (Central European Standard Time)
Now you may simply take the whole name like:
var myDate = new Date();
var userTmzn = myDate.substring(myDate.lastIndexOf('(')+1).replace(')','').trim()
and this should give you this in userTmzn
Central European Standard Time
Now to make it neat and have an abbreviation you may try some more operations:
// Take the part with timezone name and strip it from trailing ')'
var fullName = myDate.split("(")[1].replace(")","");
// Split into words
var words = fullName.split(" ");
// Take just first letters
var timezoneCode = "";
for(i = 0; i < words.length; i++)
{
timezoneCode += words[i].charAt(0);
}
That should give you (following the same example) this in timezoneCode variable:
CEST
This is highly custom, not a ready solution. You should verify in the code that default date's toString() returns date in TIME FORMAT, you should test on various browsers, etc. This is just a clue.

Does javascript new Date(timestamp) return date according to client's timezone?

I have a situation when i retrieve a timestamp from the server and use the following :-
var x = new Date(timestamp);
Does x give the time as per the client's timezone ?

First of all you have to ensure that the timestamp you put in the new Date() constructor is in Unix Time and in miliseconds, which is not always the case when you get the timestamp from a sever.
Next, the acutal Date object will just store this timestamp and provides some methods to transform it and to display it in a human readable form. Just take a look at https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Date and try some things for yourself.
One thing that it definitely does is using the correct client timezone in the toString() method:
var x = new Date(timestamp);
console.log(x); //Sat Jun 01 2013 18:00:12 GMT+0200 (Mitteleuropäische Sommerzeit)
//that was the result for my timezone

I think it gives the time according to timezone set in the client operation system.

Is there a simple conversion for this datetime format?

I'm retrieving data from a JSON feed using jQuery and as part of the feed I'm getting 'datetime' attributes like "2009-07-01 07:30:09". I want to put this information into a javascript Date object for easy use but I don't believe the Date object would recognize this kind of format if I simply plugged it into the constructor. Is there a function or maybe a clever trick I can use to quickly break down this format into something the Date object can recognize and use?

The "date" attribute you are retrieving from that webservice is not a real Date, as it is not a recognized date format.
The easiest way to handle it as a Date object would be to replace the empty space with a "T":
var receivedDate = "2009-07-01 07:30:09";
var serializedDate = new Date(receivedDate.replace(" ", "T"));
alert(serializedDate);
This is not the most correct, as it is not handling timezones, but in most cases will work.

See this and this.
input = "2009-07-01 07:30:09";
var res = input.match(/([\d\-]+) (\d+):(\d+):(\d+)/);
date = new Date(Date.parse(res[1]));
date.setHours(res[2]);
date.setMinutes(res[3]);
date.setSeconds(res[4]);
console.log(date);
Edit: My original answer was
t = new Date(Date.parse("2009-07-01 07:30:09"));
which did not throw any error in chrome but all the same incorrectly parsed the date. This threw me off. Date.parse indeed appears to be quite flaky and parsing the complete date and time with it is probably not very reliable.
Edit2: DateJS appears to be a good solution for when some serious parsing of text to date is needed but at 25 kb it is a bit heavy for casual use.

var str="2009-07-01 07:30:09";
It depends on the time zone,
and if the date string has subtracted 1 for the month.
If it is GMT time, and the 07 means July and not August:
var str="2009-07-01 07:30:09";
var d=new Date(), time;
str=str.split(/\D0?/);
str[1]-=1;
time=str.splice(3);
d.setUTCFullYear.apply(d,str);
d.setUTCHours.apply(d,time)
alert(d)
/* returned value: (Date)
Wed Jul 01 2009 03:30:09 GMT-0400 (Eastern Daylight Time) or local equivilent
*/

This may be a bit cumbersome, but the JavaScript Date object will take an argument list of YYYY,MM,DD,HH,MM,SS. Parse out the date value and pass it to a Date constructor, e.g.
var splitDT= '2009-07-01 07:30:09'.split(' '); // ['2009-07-01','07:30:09']
var d= splitDT[0].split('-');
var t= splitDT[1].split(':');
alert( (new Date(d[0],d[1],d[2],t[0],t[1],t[2])) );
Bah. Had to use the array index values instead. Yeah, that's a mess. But it works.