Untitled

<html>
    <head>
    <title> bo </title>
        <script language = "javascript" type = "text/javascript">
        function isEditabile(){
        if(document.getElementById('idTesto').disabled == true ){
        document.getElementById('idTesto').disabled = false;
        } else {
            document.getElementById('idTesto').disabled = true;
            }
        }
        </script>
    </head>
    <body>
    <input id = "idTesto" name = "testo" type = "text" value = "testo">
    <input type = "button" value = "Invio" onClick = "isEditabile();">
    </body>
</html>