Can I access to iframe 's parent's element from the iframe page

Question

First the two page in under the same domain

In the parent page.htm I have only a element like input#test,

then I set a iframe in the parent page

Answer 1

Try

var input = $(window.self.top).contents().find('input#test');

or

var input = $(window.self.top.document).find('input#test');