I'm a web design student who has designed a website for a family member in my spare time. The website uses 5 html documents and all share one css document, it has no jscript docs. Recently, we learned how to use jscript to set up an image gallery in class where clicking on a certain button changes the picture shown on the page, my question is can the same thing be applied to the contents of an html document?(<p>,<a>,<img>) I'm aware you can change the contents of say, a <p> with an id tag but I mean to do it for a whole sections of the site. That includes paragraphs, images etc.

If so, it would be great to cut down my html from 6 pages to just one.

I think you should change your question. The thing is that JS can do what you want, but should you do it? It depends on how you design a page and how you use it. It may be suitable for one case but may not be on the other. In your case, if your page consists of multiple big image files, it could slow down the load time at the beginning. However, if the page consists mostly text, then it may be better to condense all pages to one. However, you may also have to think about redesign your page. Please let me know if this answer your question.