$(document).ready(function(){
  // normal cycling blink for the elements color
  $("span").blink();
 
  // override rate, values (colors), and property to blink (background)
  $("span").blink({
    "rate":1000,
    "values": ["red", "grey", "silver"], 
    "property": "background-color"});
 
  // override the new_index function to return a random index instead
  $("span").blink({
    "new_index": 
      function(i, colors){ 
        return Math.floor(Math.random() * colors.length)
      }
    });
});

(function($){
  $.blink = {}
  $.blink.defaults = {
    "values": ["red", "orange", "yellow", "green", "aqua", "blue", "violet"],
    "rate": 150,
    "start_index": 0,
    "property": "color",
    "new_index":
      function(i, colors) {
        return (i + 1) % colors.length
      }
    }
  $.fn.blink = function(options) {
    var settings = $.extend({}, $.blink.defaults, options);
    return $(this).each(function() {
      $(this).data("blink_settings", settings);
      $(this).data("blink_index", settings.start_index);
      $(this).bind("blink.changeValue", function() {
        var $this = $(this);
        var settings = $this.data("blink_settings");
        var index = $this.data("blink_index");
        $this.css(settings.property, settings.values[index]);
        $this.data("blink_index", settings.new_index(index, settings.values));
 
        setTimeout(function() {
          $this.trigger("blink.changeValue");
        }, settings.rate);
      });
      $(this).trigger("blink.changeValue");
    });
  }
})(jQuery);