botón de palanca por JavaScript

<!DOCTYPE html>
<html>
<head></head>
<body>
<form>
<input type="button" id="myButton" value="NO"
       onclick="Buttontoggle();">
</form>
</body>
<script type="text/javascript">
function Buttontoggle()
{
  var t = document.getElementById("myButton");
  if(t.value=="YES"){
      t.value="NO";}
  else if(t.value=="NO"){
      t.value="YES";}
}
</script>
</html>
Mohamed Koraem