Can I open a new window and populate it with a string variable?

HTML

Archer's answer is a good one, but you can do this in a one liner if you wish:

window.open("data:text/html;charset=utf-8,"+html, "", "_blank")

window.open("data:text/xml;charset=utf-8,"+xml, "", "_blank")

With XML, make sure you string begins with <?xml version="1.0" encoding="UTF-8"?> and has a root element. If it doesn't, you can easily add it:

window.open('data:text/xml;charset=utf-8,<?xml version="1.0" encoding="UTF-8"?><RootTag>'+xml+'</RootTag>', "", "_blank")

Archer's answer is the best way. But you need to close the document to run the scripts inside the "htmlString".

 var wnd = window.open("about:blank", "");
        wnd.document.write(htmlString);
        wnd.document.close();

Yes it's possible...

var wnd = window.open("about:blank", "", "_blank");
wnd.document.write(html);

That should do the trick.