If JavaScript is not activated, Ajax can't works. The user must be asked to set JavaScript from within options of the browser, with the "noscript" tag.
- Since data to display are loaded dynamically, they are not part of the page, and the keywords inside are not viewed by search engines.
- The asynchronous mode may change the page with delays (when the processing on the server take some times), this may be disturbing.
- The back button may be deactivated (this is not the case in examples provided here). This may be overcomed.