opengovernment/askthem

(function($)
{
    /**
     * Auto-growing textareas; technique ripped from Facebook
     *
     * http://github.com/jaz303/jquery-grab-bag/tree/master/javascripts/jquery.autogrow-textarea.js
     */
    $.fn.autogrow = function(options)
    {
        return this.filter('textarea').each(function()
        {
            var self         = this;
            var $self        = $(self);
            var minHeight    = $self.height();
            var noFlickerPad = $self.hasClass('autogrow-short') ? 0 : parseInt($self.css('lineHeight')) || 0;

            var shadow = $('<div></div>').css({
                position:    'absolute',
                top:         -10000,
                left:        -10000,
                width:       $self.width(),
                fontSize:    $self.css('fontSize'),
                fontFamily:  $self.css('fontFamily'),
                fontWeight:  $self.css('fontWeight'),
                lineHeight:  $self.css('lineHeight'),
                resize:      'none',
                'word-wrap': 'break-word'
            }).appendTo(document.body);

            var update = function(event)
            {
                var times = function(string, number)
                {
                    for (var i=0, r=''; i<number; i++) r += string;
                    return r;
                };

                var val = self.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) + ' ' });

                // Did enter get pressed?  Resize in this keydown event so that the flicker doesn't occur.
                if (event && event.data && event.data.event === 'keydown' && event.keyCode === 13) {
                    val += '<br />';
                }

                shadow.css('width', $self.width());
                shadow.html(val + (noFlickerPad === 0 ? '...' : '')); // Append '...' to resize pre-emptively.
                $self.height(Math.max(shadow.height() + noFlickerPad, minHeight));
            }

            $self.change(update).keyup(update).keydown({event:'keydown'},update);
            $(window).resize(update);

            update();
        });
    };
})(jQuery);