[cmd]

<form method="post" action="authorization.php">
     <div class="logReg">
          <input type="text" class="loginTextField" placeholder="LOGIN" name="login">
    	  <input type="password" class="passTextField" placeholder="PASSWORD" name="password">
          <input type="submit" class="enterButton" value="Enter">
     </div>
</form>

<script>
function checkLoginAndPassFields() {

   if ( $('.passTextField').val() && $('.loginTextField').val() ) {
       $('.enterButton').show();
   } else {
       $('.enterButton').hide();
   }
}

$('.loginTextField').change(function() {
  checkLoginAndPassFields();
});

$('.passTextField').change(function() {
  checkLoginAndPassFields();
});

$('.enterButton').hide();
</script>