i've this code, but the output is:
hmm (in lowercase and plain black...)
HTML Code:
 <script type = "text/javascript">
  var astring = "";
  function teste(astring) {
   astring.toUpperCase();
   astring.fontcolor('red');
   return astring;
  }
 </script>
 
 </head>
 <body>
 
 <script language = "JavaScript">
  document.writeln(teste("hmm"));
 </script>
why this does not work?

TiA