What is the difference between GET and POST for Ajax requests?
I don't see any difference between those two, except that when I use GET, the parameters are send in URL, which for me don't really make any difference, since all requests are made on background and user doesn't find any difference.
edit: What are PUT and DELETE methods used for?
GET is designed for getting data from the server. POST (and lesser-known friends PUT and DELETE) are designed for modifying data on the server.
A GET request should never cause data to be removed from an application. If you have a link you can click on with a GET to remove data, then Google spidering your site could click on all your "Delete" links.
The canonical answer can be found here, which quotes the HTML 2.0 spec:
If the processing of a form is idempotent (i.e. it has no lasting observable effect on the state of the world), then the form method should be GET. Many database searches have no visible side-effects and make ideal applications of query forms.
If the service associated with the processing of a form has side effects (for example, modification of a database or subscription to a service), the method should be POST.
In your AJAX call, you need to use whatever method your server supports. You should always design your server so that operations that modify data are called by POST/PUT/DELETE. Other comments have links to REST, which generally maps C/R/U/D to "POST or PUT"(Create)/GET(Read)/PUT(Update)/DELETE(Delete).
If you're sending large amounts of data, or sensitive data over HTTPS, you will want to use POST. If it's just a simple parameter, I would use GET.
GET requests have a limit to the amount of data that can be sent. I forget the exact number, but this can cause issues if you're sending anything substantial.
Basically the difference between GET and POST is that in a GET request, the parameters are passed in the URL where as in a POST, the parameters are included in the message body.
Whether its AJAX or not is irrelevant. Its about the action that you're taking. I'd recommend following the principles of REST. Which have further provisions for updating, deleting, etc...
GET requests are easier to exploit in CSRF (cross site request forgery) attacks. Namely fake POST requests require Javascript to be enabled on the user side, while fake GET requests are still possible just with img, script tags.
Many web servers limit the length of the data that can be passed as part of the URL, so the GET request may break in odd ways that are hard to debug.
Also, most server software logs URLs in the access logs, so if you pass sensitive information (such as passwords) in a GET request, this will in all likelihood be written to disk in plaintext.
From a REST perspective, GET requests should have no side-effects -- they shouldn't modify data. So, if you're just GETting a resource by ID, this makes sense, but if you're committing changes to a resource, you should be using PUT, POST, or UPDATE for the http verb.
About me, i prefer POST. I reserve get to the events i know the sent value is limited to data i have the "control", for example, to retreive an item with an id. Example, "getitem?id=123", "deleteImtem?id=123", ... For the other cases, when i have a form fillable by a user, i prefer POST.
Like Ryan Smith have said, it's better to use POST to send a large amount of data, and less wories in cases of the use in others language/special chars (generally all majors javascript framework should'nt have any problems to deal with that but i think is less wories to use POST).
For the REST perspective, in my opinion, you can use this with a new project (to keep a consistency with the entire project).
Finally, maybee some programs used in a network (URL loguers (ie.: to see if the employees lost their time on non-autorised sites, ...) proxys, ... ) or any other kind of tool can intercept the query. Somes will show in the reports the params you have sent with GET, considering it like a different web page. But in this situation, is could be not your problem it's changes from a project to an other! ;)
The difference is the same between GET and POST whether you're using Ajax, HTML forms, or curl. Here are the relevant definitions:
If you are passing on any arguments with characters that can get messed up in the URL (such as spaces), you use POST. Otherwise you can use GET.
Generally, if you're just passing on a few tiny arguments you would use GET. But for passing on user submitted information such as blog entries, text, etc, its a good practice to use POST.
There are also certain frameworks that rely completely on segment based urls (such as site.com/products/133 rather than site.com/products.php?id=333 and these frameworks unset the GET variables for security. In such cases you would use POST allt the time.
