[removed]() vs inserting DOM nodes: preserve form information?

Question

Consider two web pages with the following in their body respectively:

Answer 1

document.write() won't blow away the page content as long as it is executed inline as the page is rendered. Online advertising makes extensive use of document.write() to dynamically write adverts into the page as it loads.

If however, you executed the document.write() method at a later time in the page history (after the body is completely rendered) then as Chase says, it would blow away the existing body and display the argument to document.write().

Other than that I agree that the preserving forms behaviour is really pretty browser specific, and not something you should rely on in many cases. It's a feature there to help the user rather than something for developers to be aware of or attempt to utilize.