humane.js

/*
 * Javascript Humane Dates
 * Copyright (c) 2008 Dean Landolt (deanlandolt.com)
 * Re-write by Zach Leatherman (zachleat.com)
 * Refactor by Chris Pearce (github.com/Chrisui)
 *
 * Adopted from the John Resig's pretty.js
 * at http://ejohn.org/blog/javascript-pretty-date
 * and henrah's proposed modification
 * at http://ejohn.org/blog/javascript-pretty-date/#comment-297458
 *
 * Licensed under the MIT license.
 */

;(function(root){

	var lang = {
			ago: 'Ago',
			from: '',
			now: 'Just Now',
			minute: 'Minute',
			minutes: 'Minutes',
			hour: 'Hour',
			hours: 'Hours',
			day: 'Day',
			days: 'Days',
			week: 'Week',
			weeks: 'Weeks',
			month: 'Month',
			months: 'Months',
			year: 'Year',
			years: 'Years'
		},
		formats = [
			[60, lang.now],
			[3600, lang.minute, lang.minutes, 60], // 60 minutes, 1 minute
			[86400, lang.hour, lang.hours, 3600], // 24 hours, 1 hour
			[604800, lang.day, lang.days, 86400], // 7 days, 1 day
			[2628000, lang.week, lang.weeks, 604800], // ~1 month, 1 week
			[31536000, lang.month, lang.months, 2628000], // 1 year, ~1 month
			[Infinity, lang.year, lang.years, 31536000] // Infinity, 1 year
		];

	function normalize(val, single)
	{
		var margin = 0.1;
		if(val >= single && val <= single * (1+margin)) {
			return single;
		}
		return val;
	}

	root.humaneDate = function(date, compareTo){

		if(!date) {
			return;
		}

		var isString = typeof date == 'string',
			date = isString ?
						new Date(('' + date).replace(/-/g,"/").replace(/T|(?:\.\d+)?Z/g," ")) :
						date,
			compareTo = compareTo || new Date,
			seconds = (compareTo - date +
							(compareTo.getTimezoneOffset() -
								// if we received a GMT time from a string, doesn't include time zone bias
								// if we got a date object, the time zone is built in, we need to remove it.
								(isString ? 0 : date.getTimezoneOffset())
							) * 60000
						) / 1000,
			token;

		if(seconds < 0) {
			seconds = Math.abs(seconds);
			token = lang.from ? ' ' + lang.from : '';
		} else {
			token = lang.ago ? ' ' + lang.ago : '';
		}

		/*
		 * 0 seconds && < 60 seconds        Now
		 * 60 seconds                       1 Minute
		 * > 60 seconds && < 60 minutes     X Minutes
		 * 60 minutes                       1 Hour
		 * > 60 minutes && < 24 hours       X Hours
		 * 24 hours                         1 Day
		 * > 24 hours && < 7 days           X Days
		 * 7 days                           1 Week
		 * > 7 days && < ~ 1 Month          X Weeks
		 * ~ 1 Month                        1 Month
		 * > ~ 1 Month && < 1 Year          X Months
		 * 1 Year                           1 Year
		 * > 1 Year                         X Years
		 *
		 * Single units are +10%. 1 Year shows first at 1 Year + 10%
		 */

		for(var i = 0, format = formats[0]; formats[i]; format = formats[++i]) {
			if(seconds < format[0]) {
				if(i === 0) {
					// Now
					return format[1];
				}

				var val = Math.ceil(normalize(seconds, format[3]) / (format[3]));
				return val +
						' ' +
						(val != 1 ? format[2] : format[1]) +
						(i > 0 ? token : '');
			}
		}
	};

	if(typeof jQuery != 'undefined') {
		jQuery.fn.humaneDates = function(options)
		{
			var settings = jQuery.extend({
				'lowercase': false
			}, options);

			return this.each(function()
			{
				var $t = jQuery(this),
					date = $t.attr('datetime') || $t.attr('title');

				date = humaneDate(date);

				if(date && settings['lowercase']) {
					date = date.toLowerCase();
				}

				if(date && $t.html() != date) {
					// don't modify the dom if we don't have to
					$t.html(date);
				}
			});
		};
	}
})(this);