<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">

<html>

<head>

<title>Untitled Document</title>

<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">

</head>

 

<body>

<form name="form1" method="post" action="">

  <input name="textfield" type="text" maxlength="3" onkeyup="return autoTab(this,3,event)">

  <input name="textfield2" type="text" maxlength="3" onkeyup="return autoTab(this,3,event)">

  <input name="textfield3" type="text" maxlength="3" onkeyup="return autoTab(this,3,event)">

</form>

</body>

</html>

<SCRIPT LANGUAGE="JavaScript">

            var isNN =

            (navigator.appName.indexOf("Netscape")!=-1);

            function autoTab(input,len, e) {

            var keyCode = (isNN) ? e.which : e.keyCode;

            var filter = (isNN) ? [0,8,9] :

            [0,8,9,16,17,18,37,38,39,40,46];

            if(input.value.length >= len &&

                  !containsElement(filter,keyCode)) {

                  input.value = input.value.slice(0, len);

                  input.form[(getIndex(input)+1) %

                  input.form.length].focus();

            }

                  function containsElement(arr, ele) {

                  var found = false, index = 0;

                  while(!found && index < arr.length)

                  if(arr[index] == ele)

                        found = true;

                        else

                              index++;

                              return found;

                              }

                              function getIndex(input) {

                              var index = -1, i = 0, found = false;

                              while (i < input.form.length && index == -1)

                              if (input.form[i] == input)index = i;

                              else i++;

                                    return index;

                                          }

                                          return true;

                                          }

      //  End -->

</script>