The AJAX Spider add-on integrates in ZAP a crawler of AJAX rich sites called Crawljax. You can use it to identify the pages of the targeted site. You can combine it with the (normal) spider for better results.
Options AJAX Spider screen
The AJAX Spider is an add-on for a crawler called Crawljax. The add-on sets up a local proxy in ZAP to talk to Crawljax. The AJAX Spider allows you to crawl web applications written in AJAX in far more depth than the native Spider. Use the AJAX Spider if you may have web applications written in AJAX.
Note: Ajax Spider add-one can enable when you pentesting in web scan mode.
How to enable AJAX Spider mode in pac config file?
You can enable the
AjaxSpider key inside web scan on the yaml file.