62 lines
2.1 KiB
JavaScript
62 lines
2.1 KiB
JavaScript
/* Friendly timezone abbreviations in client-side JavaScript
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`tzAbbr()` or `tzAbbr(new Date(79,5,24))`
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=> "EDT", "CST", "GMT", etc.!
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There's no 100% reliable way to get friendly timezone names in all
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browsers using JS alone, but this tiny function scours a
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stringified date as best it can and returns `null` in the few cases
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where no friendly timezone name is found (so far, just Opera).
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Device tested & works in:
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* IE 6, 7, 8, and 9 (latest versions of all)
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* Firefox 3 [through] 16 (16 = latest version to date)
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* Chrome 22 (latest version to date)
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* Safari 6 (latest version to date)
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* Mobile Safari on iOS 5 & 6
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* Android 4.0.3 stock browser
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* Android 2.3.7 stock browser
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* IE Mobile 9 (WP 7.5)
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Known to fail in:
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* Opera 12 (desktop, latest version to date)
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For Opera, I've included (but commented out) a workaround spotted
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on StackOverflow that returns a GMT offset when no abbreviation is
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found. I haven't found a decent workaround.
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If you find any other cases where this method returns null or dodgy
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results, please say so in the comments; even if we can't find a
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workaround it'll at least help others determine if this approach is
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suitable for their project!
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*/
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define([], function() {
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return function (dateInput) {
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var dateObject = dateInput || new Date(),
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dateString = dateObject + "",
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tzAbbr = (
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// Works for the majority of modern browsers
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dateString.match(/\(([^\)]+)\)$/) ||
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// IE outputs date strings in a different format:
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dateString.match(/([A-Z]+) [\d]{4}$/)
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);
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if (tzAbbr) {
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// Old Firefox uses the long timezone name (e.g., "Central
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// Daylight Time" instead of "CDT")
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tzAbbr = tzAbbr[1].match(/[A-Z]/g).join("");
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}
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// Uncomment these lines to return a GMT offset for browsers
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// that don't include the user's zone abbreviation (e.g.,
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// "GMT-0500".) I prefer to have `null` in this case, but
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// you may not!
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// First seen on: http://stackoverflow.com/a/12496442
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// if (!tzAbbr && /(GMT\W*\d{4})/.test(dateString)) {
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// return RegExp.$1;
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// }
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return tzAbbr;
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};
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});
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