We have an application that uses quite a bit of Ajax and this caused problems in recording tests using the Selenium IDE. Each test step was recorded successfully, but because there are web services calls firing in the background on the client (the Ajax stuff), a playback would fail immediately. The fix in general is to use Javascript to check for a completion flag of some sort, but the IDE did not have a provision for inserting code automatically or to delay each test step.  This limited the ability to rerun a recorded test when mistakes are made during the recording process. I’ve been working (with other engineers) on modifying the Selenium IDE code to allow the automatic insertion of Ajax rendering complete Javascript code. However, the latest version of the IDE in SVN has a slow-down control now and that seems to work like a champ on our app.  It allows you to slow the playback down to something that approximates human speed and our app now seems to be happy as we record and then play back.  Thanks to the Selenium IDE developer Shinya Kasatani for this great addition.

I still plan to add a switch to allow specified Javascript to be executed automatically when the Selense plays back – to allow a check for a "render complete" flag that we have in our Javascript.