"An often-asked question on the
selenium-users
mailing list is how to test
Ajax-specific functionality with Selenium. The problem with Ajax testing is that
the HTML page under test is modified asynchronously, so a plain Selenium assert or verify command might very well fail because
the element being tested has not been created yet by the Ajax call. A
quick-and-dirty solution is to put a pause command before the assert, but this is error-prone, since the
pause might be not sufficient on a slow machine, while being unnecessarily slow
on a faster one."