putting html inside an iframe (using javascript)

Question

Can I create an empty iframe as a placeholder to later insert html into it?

In otherwords, suppose I have an empty iframe with an id,

How do I insert html i

Answer 1

iframeElementContainer =   document.getElementById('BOX_IFRAME').contentDocument;
iframeElementContainer.open();
iframeElementContainer.writeln("hello");
iframeElementContainer.close();