jQuery.fn.autoheight = function(options) {
	this.filter('textarea').each(function() {
    	var $this   	= $(this);
        var minHeight   = (options.h) ? options.h : $(this).height();
        var lineHeight  = $this.css('lineHeight');
		
		var shadow = $('<div></div>').css({
			position:   'absolute',
			top:        -10000,
			left:       -10000,
			width:      parseInt($(this).css('width')) - parseInt($this.css('paddingLeft')) - parseInt($this.css('paddingRight')),
			fontSize:   $this.css('fontSize'),
			fontFamily: $this.css('fontFamily'),
			lineHeight: $this.css('lineHeight'),
			resize:     'none'
		}).appendTo(document.body);
		
		var update = function() {
			var times = function(string, number) {
				for (var i = 0, r = ''; i < number; i ++) r += string;
				return r;
			};
			var val = this.value.replace(/</g, '&lt;')
								.replace(/>/g, '&gt;')
								.replace(/&/g, '&amp;')
								.replace(/\n$/, '<br/>&nbsp;')
								.replace(/\n/g, '<br/>')
								.replace(/ {2,}/g, function(space) { return times('&nbsp;', space.length -1) + ' ' });

			shadow.html(val);
			$(this).css('height', Math.max(shadow.height() + parseInt(lineHeight) + 1, minHeight));
		}
		$(this).change(update).keyup(update).keydown(update);
		update.apply(this);
	});
	
	return this;
};