Is too much Ajax a bad thing?

Question

I'm developing a site with a client side javascript framework (dojo/dijit) at the moment. As with all javascript/framworks you start using Ajax to do quick calls and updates. My question is there a general rule of thumb when to use Ajax and when to use a link? I only ask because I seem to be using Ajax more then not and I'm worried that any errors in the initial page might propagate to other elements. Or with content getting constantly replaced something might go wrong.

I suppose what I'm asking is there any downfalls to heavy Ajax usage in a web pages?

EDIT

SEO - not an issue. I'm just thinking of client server issues for now. Links would bet Ajax hands down if you wanted good SEO

Answer 1

In my mind, there are three issues with using tons of AJAX calls.

The first is from a user perspective. If I am doing a lot of navigation, as a user, I want to be able to use my back/forward buttons in my browser and have them work correctly. If they do, then there isn't an issue. If they don't, you've broken fundamental navigation in my browser.

Second is bookmarking/indexing. As a user, I may want to bookmark something so I can come back to it or share it. As an indexer for a search engine, you as a developer want to let the search engine "see" all the pages of information you have so that people can find your site. Both of these require some sort of unique url.

Third is debugging from a development point of view. The more random stuff you are throwing on a page and/or replacing dynamically, the harder it gets to track down what's wrong. The more you have the more that needs to be integrated well or could interact badly.