codice:
<!DOCTYPE HTML PUBLIC “-//W3C//DTD HTML 4.01 Transitional//EN”>
<html>
 <head>
  <meta http-equiv=”Content-Type” content=”text/html; charset=iso-8859-1″>
  <title>Validate form</title>
  <script type="text/JavaScript">
   function isValidEmail() {
     var emailAddress = document.form.emailAddressField.value;
     var regExpEmail = /^([a-zA-Z0-9_.-])+@(([a-zA-Z0-9-])+.)+([a-zA-Z0-9]{2,4})+$/;
     
     if (emailAddress.length == 0) {
      alert ("The field is empty. Try again!");
     } else if (regExpEmail.test(emailAddress)) {
      document.form.emailAddressField.focus();
      document.form.emailAddressField.select();
      varCopyEmailAddress = document.form.emailAddressField.createTextRange();
      varCopyEmailAddress.execCommand("Copy");
      document.form.emailAddressField.value = "";
      document.form.emailAddressField.blur();
      alert(emailAddress + " is valid e-mail address and it is copied into notes!")
     } else {
      alert (emailAddress + " is not valid e-mail. Please try again!");
     }
    }
     
    function clearEmailAddressField() {
      var emailAddress = document.form.emailAddressField.value;
      
     if (emailAddress.length == 0) {
      alert ("The field is empty!);
     } else {
      document.form.emailAddressField.value = "";
     }
    }
  </script>
 </head>
 <body>
  <form name="form">
   <h5>Validate your e-mail address</h5>
   <input type="text" name="emailAddressField" placeholder="validate your e-mail address" size="35"></input>
   <button type="button" onclick="isValidEmail()">Validate e-mail address</button>
   <button type="button" onclick="clearEmailAddressField()">Clear e-mail address field</button>
  </form>
 </body>
</html>
...come faccio a far si che la copia del testo negli appunti avvenga anche in Mozzilla Firefox e Google Chrome (ho provato con document.form.emailAddressField.createRange() e altre varianti ma...)?