How do I know if Quirks mode was triggered within IE6?

Question

I read that if the DOCTYPE is not corectly set IE6 will enter Quirks mode.

I have given a document HTML 4.01 Transitional, but how do I know if IE6 triggers Quirks mode or not?

Answer 1

Look at document.compatMode

<script type="text/javascript" charset="utf-8">
  if(document.compatMode == 'CSS1Compat'){
    alert("Standards mode");
  }else{
    alert("Quirks mode");
  }
</script>