How can we stop caching when using AJAX

[sourabh]

I have following situation where I’m facing problem because of the caching

There are number of check boxes. I want to store value of check box in session when it is checked and remove that value when it is unchecked again.

I have called one php page through AJAX passing it value of the check box. The AJAX request is made on click event of check box.

It just work file when for the first time you check or uncheck checkbox. After that it won’t work.
If you clear cache and do it again, it works again in the same way.

I think the code simply ignore the request if it was made previously.

Is there any solution to this problem?

Many thanks (In advance)

[apfritts]

Add an extra field to the query string (something random like "neverused") and then set its value to a random number. I use the JavaScript Date() function:

var d = new Date();
url += "neverused="+d.getTime();

d.getTime() returns the number of milliseconds since some time back in the 80's.

[MarkR]

AJAX requests made by browsers generally following similar caching rules to everything else.

So set a correct Expires: header, and/or other headers (Last-modified is always good to get caching) , and it will work.

Generally speaking, setting "Expires:" in the past is a good idea. Read the relevant RFCs for more info.

Don't add random query string rubbish - that doesn't stop it caching, just pollutes its cache with junk.

Mark