[jQuery] 403 error in Firefox fixed, but not sure why it worked

[brianwilkins]

I added the following to one of my files to hide and show a group of
thumbnails and it gave me a 403 error in Firefox only:

$(document).ready(function(){
        $('div.more').hide();
        $('br.clearbothMore').hide();
        $('h2.contract').hide();

        $('h2.expand').click(function()
                {
                        $('div.more').toggle('crawl');
                        $('br.clearbothMore').toggle('crawl');
                        $('h2.expand').hide();
                        $('h2.contract').show();
                        return false;
                });


        $('h2.contract').click(function()
                {
                        $('div.more').toggle('crawl');
                        $('br.clearbothMore').toggle('crawl');
                        $('h2.expand').show();
                        $('h2.contract').hide();
                        return false;
                });
  });


I modified it to this and the 403 error disappeared:

$(document).ready(function(){
        $('div.more').hide();
        $('br.clearbothMore').hide();
        $('h2.contract').hide();});

  //this $(document.ready is new
  $(document).ready(function(){
        $('h2.expand').click(function()
                {
                        $('div.more').toggle('crawl');
                        $('br.clearbothMore').toggle('crawl');
                        $('h2.expand').hide();
                        $('h2.contract').show();
                        return false;
                });


        $('h2.contract').click(function()
                {
                        $('div.more').toggle('crawl');
                        $('br.clearbothMore').toggle('crawl');
                        $('h2.expand').show();
                        $('h2.contract').hide();
                        return false;
                });
  });

I'm just wondering why adding the extra $(document).ready made it
work? I would like to understand it, so I can avoid any future
problems.

Thanks!