Date.pretty.js

// Auto-updating Date stuff

Date.pretty = new Class({
	
	Implements: Options,
	
	options: {
		interval: 60000,
		threshold: '24 hours'
	},
	
	initialize: function(elements, options){
		this.setOptions(options);
		this.elements = [];
		this.dates = [];
		
		var bits = this.options.threshold.match(/(\d+)\s*(second|minute|hour|day|week|month|year)?/i);
		this.threshold = (!bits) ? 0 : new Date().decrement( (bits[2] || 'day').toLowerCase(), +bits[1] );
		
		return this.include(elements);
	},
	
	update: function(){
		this.elements.each(function(element, i){
			element.set('text', this.dates[i].timeDiffInWords());
		}, this);
		
		this.timer = this.update.delay(this.options.interval, this);
		return this;
	},
	
	include: function(elements){
		$$(elements).each(function(element){
			if (this.elements.contains(element)) return;
			
			var date = Date.parse( element.get('text').clean() );
			if (date.isValid() && date > this.threshold){
				this.dates.push(data);
				this.elements.push(element);
			}
		}, this);
		
		return this.update();
	}
	
});