Include javascript and css dynamically

Some script I must post here in case of my bad memory. Maybe useful for my blog visitors.

 1  var  getHead  =   function () {
 2                   return  document.getElementsByTagName( " head " )[ 0 ];
 3              };
 4               var  includeJavascriptFile  =   function (url) {
 5                   if  (document.body  ==   null ) {
 6                      document.write( " <script src=' "   +  url  +   " ' type='text/javascript'></script> " );
 7                  }  else  {
 8                       var  script  =  document.createElement( " script " );
 9                      script.type  =   " text/javascript " ;
10                      script.language  =   " JavaScript " ;
11                      script.src  =  url;
12                      getHead().appendChild(script);
13                  }
14              };
15               var  includeCssFile  =   function (url) {
16                   if  (document.body  ==   null ) {
17                      document.write( " <link rel='stylesheet' href=' "   +  url  +   " ' type='text/css'/> " );
18                  }  else  {
19                       var  link  =  document.createElement( " link " );
20                      link.setAttribute( " rel " ,  " stylesheet " );
21                      link.setAttribute( " type " ,  " text/css " );
22                      link.setAttribute( " href " , url);
23                      getHead().appendChild(link);
24                  }
25              }