(function($){

	$.fn.autoGrowInput = function(o) {

		o = $.extend({
			maxWidth: 1000,
			minWidth: 0,
			comfortZone: 70
		}, o);

		this.filter('input:text').each(function(){

			var minWidth = o.minWidth || $(this).width(),
				val = '',
				input = $(this),
				testSubject = $('<tester/>').css({
					position: 'absolute',
					top: -9999,
					left: -9999,
					width: 'auto',
					fontSize: input.css('fontSize'),
					fontFamily: input.css('fontFamily'),
					fontWeight: input.css('fontWeight'),
					letterSpacing: input.css('letterSpacing'),
					whiteSpace: 'nowrap'
				}),
				check = function() {

					if (val === (val = input.val())) {return;}

					// Enter new content into testSubject
					var escaped = val.replace(/&/g, '&amp;').replace(/\s/g,'&nbsp;').replace(/</g, '&lt;').replace(/>/g, '&gt;');
					testSubject.html(escaped);

					// Calculate new width + whether to change
					var testerWidth = testSubject.width(),
						newWidth = (testerWidth + o.comfortZone) >= minWidth ? testerWidth + o.comfortZone : minWidth,
						currentWidth = input.width(),
						isValidWidthChange = (newWidth < currentWidth && newWidth >= minWidth)
											 || (newWidth > minWidth && newWidth < o.maxWidth);

					// Animate width
					if (isValidWidthChange) {
						input.width(newWidth);
					}

				};

			testSubject.insertAfter(input);

			$(this).bind('keyup keydown blur update', check);

		});

		return this;

	};

})(jQuery);