risolto

codice:
<head>
<SCRIPT language="javascript" type="text/javascript">
function disabilita(f,bool){
  for(var k=0;k<f.elements.length;k++){
    if(f.elements[k].type=='text'){
      f.elements[k].disabled=bool
    }
  }
}
</SCRIPT> 
</head> 

<body> 
<FORM name="prova"> 

Aletezza (m)
 

<input type=text disabled name="requiredaltezza" size=6>

 

Peso (kg)

<input type=text disabled name="requiredpeso" size=6>



<input type="checkbox" checked onclick="disabilita(this.form, this.checked)" />
<INPUT TYPE="SUBMIT" VALUE="Spedisci"></INPUT> 


</body>