how to get the html text length without set it to a textfield?

how to get the html text length without set it to a textfield?

in actionscript ,i didn't find a direct way to get the actually string's
length of a html text.here's how i get things work
var myText:String = "<p>This is <b>some</b> content to <i>render</i> as
<u>HTML</u> text.</p>";
myTextBox.htmlText = myText;
trace(myTextBox.length);
deal with large content of html text would be a performance problem.
is there a way i can get the length while i don't have to pass it to a
text device?