Detect timezone abbreviation using JavaScript

The Date object doesn't have a method for getting the timezone abbreviation, but it is implicit at the end of the result of toString. For example,

var rightNow = new Date();
alert(rightNow);

...will return something like Wed Mar 30 2011 17:29:16 GMT-0300 (ART). The timezone abbreviation can be isolated between parentheses:

var rightNow = new Date();
alert(String(String(rightNow).split("(")[1]).split(")")[0]);

The output will be the timezone abbreviation, like ART.

A native solution:

var zone = new Date().toLocaleTimeString('en-us',{timeZoneName:'short'}).split(' ')[2]
console.log(zone)

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Date/toLocaleDateString

You can pass undefined instead of en-us to default to the browser's current locale.

moment-timezone includes an undocumented method .zoneAbbr() which returns the time zone abbreviation. This also requires a set of rules which are available to select and download as needed.

Doing this:

<script src="moment.js"></script>
<script src="moment-timezone.js"></script>
<script src="moment-timezone-data.js"></script>
<script>
    moment().tz("America/Los_Angeles").zoneAbbr();
</script>

Returns:

'PDT' // As of this posting.

Edit (Feb 2018)

Evan Czaplicki has worked on a draft proposal to add a time zone API to browsers.