codice:
  <html>
    <head>

      <script type="text/javascript" language="JavaScript">
      <!--

        var artList = new Array( );

        artList[artList.length] = "maglietta";
        artList[artList.length] = "maglione";
        artList[artList.length] = "maglia da lavoro";
        artList[artList.length] = "scarpa";
        artList[artList.length] = "scarpino";
        artList[artList.length] = "calzino";
        artList[artList.length] = "calzettone";
        artList[artList.length] = "cavallo";
        artList[artList.length] = "cavalluccio marino";


        function updateList( __hForm, __hArtName )
        {
          var itemFound    = 0;
          var artToSearch  = __hArtName.value.toLowerCase( );
          var artListFound = "";

          for ( var i=0; i<artList.length; i++ )
          {
            if ( artToSearch == artList[i].substring( 0, artToSearch.length)  )  {
              artListFound += artList[i] + "\r\n";
              itemFound++;
            }
          }

          if ( itemFound )
            artListFound = "Trovati " + itemFound + " elementi.\r\n" + artListFound;
          else
            artListFound = "Nessun articolo trovato.";

          __hForm.elements["artList"].value = artListFound;
        }


      //-->
      </script>

    </head>

    <body> 

      <form>
        Digita articolo da cercare:

        <input type="text" name="artName" onkeyup="updateList( this.form, this );" />


        



        Articoli trovati:

        <textarea rows="10" cols="20" name="artList"></textarea>
      </form>


    </body> 

  </html>