jQuery plugin sample: Twitter-like dynamic character countdown for textareas

gistfile1.js

/*
    jQuery plugin sample: Twitter-like dynamic character countdown for textareas

    Example:

      $('#textarea').countdown({
        limit: 140,
        init: function(counter){
          $('#counter').css('color','#999999').val(counter);
          $('#submit').attr('disabled','disabled');
        },
        plus: function(counter){
          $('#counter').css('color','#999999').val(counter);
          $('#submit').removeAttr('disabled');
        },
        minus: function(counter){
          $('#counter').css('color','red').val(counter);
          $('#submit').attr('disabled','disabled');
        }
      });
*/
(function($) {
  $.fn.countdown = function(config) {
    var options = $.extend($.fn.countdown.defaults, config);
    return this.each(function() {
      $(this).bind('keyup change', function() {
        if(!$(this).val().length){
          options.init(options.limit);
          return;
        }
        var available = options.limit - $(this).val().length;
        var counter = options.prefix + available + options.suffix;
        if (counter >= 0)
          options.plus(counter);
        else
          options.minus(counter);
      });
    });
  };
  $.fn.countdown.defaults = {
    limit: 140,
    init: function(counter){},
    plus: function(counter){},
    minus: function(counter){},
    prefix: '',
    suffix: ''
  };
})(jQuery);