My HTML-written website has several pages with similar codings written for the appearance and functioning of the top navigation bar. How can I extract that part of the codes by Javascript so that when I want to make changes to the top navigation bar, I can just change that external file for once and don’t need to make the same changes repeatedly for every pages. And also can I preview these Javascript-webpages in my own computer before publishing it to the webhosting computer. Thanks a lot in advance.
Thank you for the iframe advice. But I’ve heard that frame is not good for seach engines, is it? If frame is really not good for search engines, is there other way to achieve my end?