why is the insertBefore showing error

I intend to create a new Div element via javascript, but i am having problem appending my code to the DOM

               <div id="container">
                   <div id="content">
                   </div
               </div>
            <script>
                var container = document.getElementById('container');
                function divCreate()   {

                     var newDiv = document.createElement('div');

                     var newContent = document.createTextNode('Hello 

                     this is a div is added via javasceipt);   

                     newDiv.appendChild(newContent);

                     var currentDiv = document.getElementById('content');

                     document.body.container.insertBefore(newDiv,   
                     currentDiv
                }

              divCreate();

         </script>

 my actual intention was to insert the new div before the content inside the

container. I do understand the DOM as a tree of objects and hierarchy too.I thought that i could navigate the tree via this hierarchy . that is from document--->body----->container.

It did worked on the container, but not the content div. Could someone please tell what I am missing here?