How to detect if client is able to BOLD text with execCommand()

I am making a WYSIWYG editor from scratch using execCommand(). I want to disable my formatting buttons (alignment, bold, italicize, underline, color, size, family, etc) when the user has no text selected.

I have the document code inside of an IFRAME, and outside of the IFRAME are the buttons/scripts. I made the iframe's document contentEditable and turned designMode on.

What exactly can I do to find out if any text is selected?

If possible, how can I find out if the user has their cursor anywhere inside of a DIV element for text alignment? I am sure I could use this to detect if the cursor is inside of an already-bolded text or similar, too.

<iframe src="/builder/ajax/load?id=1"></iframe>
<script type="text/javascript">
  function init() {
     // editor is defined in another script as the iframe.contentWindow.document
     editor.body.contentEditable = "true";
     editor.body.designMode = "on";
  }
</script>

Solution

This can be done using queryCommandSupported and queryCommandEnabled as I just now discovered!