AJAX in the TYPO3 BackendΒΆ

In TYPO3 4.2 a new model for writing AJAX code in the TYPO3 Backend was introduced. Although there were some parts in the TYPO3 Backend that used AJAX already, they are now unified into a single interface that handles errors and dispatches the different calls to their final locations. This way it is ensured that e.g. a BE user is logged in and all TYPO3 variables are loaded.

The whole architecture builds on top of successful techniques developers already know. It's a mixture between the eID concept from the TYPO3 Frontend, the hooking idea we know from other places in TYPO3, piped through the single entrypoint file index.php?ajaxID=foobar that creates a PHP AJAX object to see if an error occurred or not. If something went wrong, the X-JSON header is set to false and the client-side AjaxRequestHandler will know that there is an error.