Autogrow Textareas in jQuery

jquery.autogrow.js

/*
 * jquery.autogrow.js
 *
 * A plugin written for UserVoice that makes it easy to create textareas
 * that automatically resize to fit their contents.
 *
 * Based on Scott Moonen's original code for Prototype.js:
 *
 * <http://scottmoonen.com/2008/07/08/unobtrusive-javascript-expandable-textareas/>
 *
 * Author: John W. Long <[email protected]>
 *
 */
;(function($) {
  $.fn.autogrow = function() {
    return this.filter('textarea').each(function() {
      if (!$(this).data('autogrow-applied')) {
        var textarea   = $(this)
        ,   expander   = $('<div />').css({'position': 'absolute', 'visibility': 'hidden', 'top': '-99999px'})
        ,   escaper    = $('<span />')
        ,   properties = ['-webkit-appearance', '-moz-appearance', '-o-appearance', 'appearance', 'font-family', 'font-size', 'font-weight', 'font-style', 'border', 'border-top', 'border-right', 'border-bottom', 'border-left', 'box-sizing', 'padding', 'padding-top', 'padding-right', 'padding-bottom', 'padding-left', 'min-height', 'max-height', 'line-height']
        ,   timer      = null
        ;

        $.each(properties, function(i, p) { expander.css(p, textarea.css(p)); });
        $(textarea).after(expander);

        function sizeTextarea() {
          clearTimeout(timer);
          timer = setTimeout(function() {
            var value = escaper.text(textarea.val()).text().replace(/\n/g, '<br />') + '<br>z<br>z';
            expander.html(value);
            expander.css('width', textarea.innerWidth() + 'px');
            textarea.css('height', expander.innerHeight() + 'px');
          }, 100); // throttle by 100ms 
        }

        textarea.bind('input.autogrow propertychange.autogrow', sizeTextarea)

        sizeTextarea();

        textarea.data('autogrow-applied', true);
      }
    });
  };
}(jQuery));