Posts Tagged ‘ AJAX ’

Best Practices: Using AJAX

Monday, June 2nd, 2008 By Nikhil

Use GET for AJAX Requests

It has been found that when using XMLHttpRequest, POST is implemented in the browsers as a two-step process: sending the headers first, then sending data. So it’s best to use GET, which only takes one TCP packet to send (unless you have a lot of cookies). The maximum URL length in IE is 2K, so if you send more than 2K data you might not be able to use GET.
An interesting side affect is that POST without actually posting any data behaves like GET. GET is meant for retrieving information, so it makes sense (semantically) to use GET when you’re only requesting data, as opposed to sending data to be stored server-side.

Avoid Synchronous AJAX Calls

When making “Ajax” requests, you may choose either async or sync mode. Async mode runs the request in the background while other browser activities can continue to process. Sync mode will wait for the request to return before continuing.
Requests made with sync mode should be avoided. These requests will cause the browser to lock up for the user until the request returns. In cases where the server is busy and the response takes a while, the user’s browser (and maybe OS) will not allow anything else to be done. In cases where a response is never properly received, the browser may continue to block until the request is timed out.
If you think that your situation requires sync mode, it is most likely time to re-think your design. Very few (if any) situations actually require Ajax requests in sync mode.

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