How do you keep content from your previous web page after clicking a link?

Question

I'm sorry if this is a newbie question but I don't really know what to search for either. How do you keep content from a previous page when navigating through a web site? For example, the right side Activity/Chat bar on facebook. It doesn't appear to refresh when going to different profiles; it's not an iframe and doesn't appear to be ajax (I could be wrong).

Thanks,

Answer 1

I believe what you're seeing in Facebook is not actual "page loads", but clever use of AJAX or AHAH.

So ... imagine you've got a web page. It contains links. Each of those links has a "hook" -- a chunk of JavaScript that gets executed when the link gets clicked.

If your browser doesn't support JavaScript, the link works as it normally would on an old-fashioned page, and loads another page.

But if JavaScript is turned on, then instead of navigating to an HREF, the code run by the hook causes a request to be placed to a different URL that spits out just the HTML that should be used to replace a DIV that's already showing somewhere on the page.

There's still a real link in the HTML just in case JS doesn't work, so the HTML you're seeing looks as it should. Try disabling JavaScript in your browser and see how Facebook works.

Live updates like this are all over the place in Web 2.0 applications, from Facebook to Google Docs to Workflowy to Basecamp, etc. The "better" tools provide the underlying HTML links where possible so that users without JavaScript can still get full use of the applications. (This is called Progressive Enhancement or Graceful degradation, depending on your perspective.) Of course, nobody would expect Google Docs to work without JavaScript.