Javascript time conversion functions

gistfile1.txt

	/*
	* Calculates the Twitter time since the tweet was created
	* Based on http://www.jquery4u.com/api-calls/calculate-twitter-time-tweet-javascript/
	* @param obj with datetime (e.g. git time etc). and limitSwitch (optional) in minute --- any dates beyond that will be in date in string
	* @return time since in html
	*/
	var calculateSince = function ( _parameter ) {
		var _datetime = _parameter.dateTime.replace(/\-/g,'/');
		var _limitSwitch = (_parameter.limitSwitch) ? _parameter.limitSwitch : 4320; /* optional */

		var _tTime = new Date(_datetime);
		var _cTime = new Date();
		var _sinceMin = Math.round((_cTime - _tTime) / 60000);
		var _since = '';
		var _sinceHr = 0;
		var _sinceDay = 0;
		var _sinceSec = 0;

		switch (true) {
			case _sinceMin === 0 :
			_sinceSec = Math.round((_cTime - _tTime) / 1000);
			if (_sinceSec < 10) {
				_since = 'less than 10 seconds ago';
			} else {
				_since = _sinceSec +' seconds ago';
			}
			break;
			case _sinceMin === 1 :
			_sinceSec = Math.round((_cTime - _tTime) / 1000);
			if (_sinceSec == 30) {
				_since = 'half a minute ago';
			} else if (_sinceSec < 60) {
				_since = 'less than a minute ago';
			} else {
				_since = '1 minute ago';
			}
			break;
			case _sinceMin < 45 :
			_since = _sinceMin + ' minutes ago';
			break;
			case _sinceMin > 44 && _sinceMin < 60 :
			_since = 'about 1 hour ago';
			break;
			case _sinceMin < 1440 :
			_sinceHr = Math.round(_sinceMin / 60);
			if (_sinceHr == 1) {
				_since = 'about 1 hour ago';
			} else {
				_since = 'about ' + _sinceHr + ' hours ago';
			}
			break;
			case _sinceMin > 1439 && _sinceMin < 2879 :
			_since = '1 day ago';
			break;
			case _sinceMin > 2880 && _sinceMin < _limitSwitch :
			_sinceDay = Math.round(_sinceMin / 1440);
			_since = _sinceDay + ' days ago';
			break;
			default :
			_since = _datetime;
			break;
		}

		return _since;
	};
	
/*
	* Converts unixtime stamp (you need to make sure that the time stamp is UTC) to UTC Date in string.
	* reference : http://d.hatena.ne.jp/yutakikuchi/20111015/1318633937
	* @param unixtime stamp
	* @return UTC Date in string.
	*/
	var convertUnixTimestampToDateTime = function (_unixTimestamp ) {
		return _dateUTCString = new Date( _unixTimestamp * 1000 ).toUTCString();
	};
	
/*
	* Converts time in string to unix timestamp
	* reference : http://d.hatena.ne.jp/yutakikuchi/20111015/1318633937
	* @param time in string
	* @return UTC Date in string.
	*/
	var convertDateTimeToUnixTimestamp = function ( _dateTime ) {
		return Date.parse( _dateTime.replace( /-/g, '/') ) / 1000;
	};
	
/*

todo:
more conversion routines
php version of above ...
UTC <-> local time conversion
*/