How to disable button in action

[onh1986]

Hello
Take a look at this code

<?php
if ($v == "1") {
  --"ACTIONS WHICH I WANT TO DO"--
  exit();
}

echo "<form action=file.php method=post>";
echo "<input type=hidden name=v value=1>";
echo "<input type=submit value=Go>";
echo "</form>";
?>

What I want how can I disable the button "Go" after I'd clicked on it.
I know it needs JS, how can I do it by JS?