Ckeditor update textarea

I am trying to get the ckeditor working. Obviously it doesn't make use of the textarea so on submit the form doesn't submit the text in the editor. Beceause I make use of polymorphic associations etc. I can't make a onsubmit function to get the value of the textarea (when the form is submitted) .

So I found this question: Using jQuery to grab the content from CKEditor's iframe

with some very good answers. The answers posted there keep the textarea up to date. That is very nice and just what I need! Unfortunately I can't get it to work.
Does somebody know why (for example) this doesn't work?

I have a textarea (rails but it just translates to a normal textarea):

<%= f.text_area :body, :id => 'ckeditor', :rows => 3 %>

And the following js:

if(CKEDITOR.instances.ckeditor ) {
  CKEDITOR.remove(CKEDITOR.instances.ckeditor);
}
CKEDITOR.replace( 'ckeditor',
{
skin : 'kama',
toolbar :[['Styles', 'Format', '-', 'Bold', 'Italic', '-', 'NumberedList', 'BulletedList', 'Link']]});


CKEDITOR.instances["ckeditor"].on("instanceReady", function()
{
//set keyup event
this.document.on("keyup", CK_jQ);

//and paste event
this.document.on("paste", CK_jQ);
}

function CK_jQ()
{
 CKEDITOR.instances.ckeditor.updateElement(); 
}

I get the following "error" in my firebug.

missing ) after argument list
[Break on this error] function CK_jQ()\n