Moment.js a jQuery plugin that helps you display time and dates. It’s a simple JavaScript date library for parsing, validating, manipulating, and formatting dates.

moment jQuery plugin for validating date formats

Moment Timezone

You can also check out what time is it NOW for country TO country. Still you can download the entire World timezone and add that timezone in your websites. The minified source is sized at 1.8kb and the size of Full Source is 11.1kb.

Moment Timezone with jQuery Worldwide