You can clone with
<div class="preview" style="visibility: hidden">
<iframe src='preview.html' id="preview"></iframe>
* load in index.html page
// After index.html page was loaded, iframe turn visible.
// Because of the case, preview.html in iframe was loaded is faster than index.html was loaded,
// js was loaded in index.html can't move.
* load in preview.html page
The page name is index.html has iframe window in itself, The iframe page is preview.html
If you want to handling iframe element by js loaded in index.html, That case can't handling if iframe was loaded faster than index.html.
And to no effect links or input tags,You load js that is changes no effect by preview.html better.