What is the Ajax,ajax scenario where the cache is generated and how does the cache problem be resolved? Some places in the project do not recommend using Ajax, why?

The full name of Ajax is asynchronous JavaScript and XML (asynchronous JavaScript and XML). Able to implement partial refresh page.
The situation that generated the cache:
After the success of the data sent by Ajax, the requested URL and the returned response results are saved in the cache, and the next time Ajax sends the same request, it takes out the data directly from the cache, in order to improve the response speed and user experience of the page. Currently this requires two request URLs to be identical, including parameters. At this point, the browser will not interact with the server.
To resolve the caching scheme:
The most effective way to solve this problem is to prevent page caching, and there are several ways to deal with it:
1, in the AJAX send the request before adding Xmlhttprequest.setrequestheader ("Cache-control", "No-cache");
2, in the service End plus header ("Cache-control:no-cache, must-revalidate");
3, in the AJAX send the request before adding Xmlhttprequest.setrequestheader ("if-modified-since", "0″);"
4, after the Ajax URL parameters plus "? fresh=" + math.random (); Of course, the parameter fresh can be arbitrarily taken.
5, the fifth method is similar to the fourth, after the URL parameter plus "? timestamp=" + New Date (). GetTime ();
6. Replace get with post: not recommended
Use NOT recommended:
1, Ajax does not support the browser back button.
2. Security issues Ajax exposes the details of interacting with the server.
3, the search engine support is weaker.
4, the failure of the program's abnormal mechanism.
5, not easy to debug.