AS3 RegExp engine (and ECMAScript based JavaScript) do not support complex "lookbehind" expressions. (lookahead expressions are fully supported.)
For example:
(?<=<body>)(.*?)(?=<\/body>)
will work but;
(?<=<body\b[^>]*>)(.*?)(?=<\/body>)
will not work in AS3.
What I need is to match a complex prefix but exclude it in the final match. In the example above; I'm trying to get the body contents in an HTML text but NOT the opening and closing body tags. And the actual test text looks like this:
<body bgcolor="#EEEEEE">
Some content here...
</body>
I think you want var regExp:RegExp = /<body>(.*?)<\/body>/i;
as opposed to the 3 groups in your current regexp, so you're only capturing the body tag, you can then reference the match with either \1 or $1 depending on which function you're using:
http://livedocs.adobe.com/flex/3/html/help.html?content=12_Using_Regular_Expressions_09.html