AJAX call appears cached for about 2 minutes on Mac - ajax

Question

I have an Ajax widget that monitors the status of a connection on a web page, and alerts the user when the server can no longer be reached. It works on Windows 7, but fails on Mac OSX 10.5.8 (both Safari and Firefox).
The crucial code is here:
(function(e){
e.fn.checknet=function(config){
function checkConnection(config){
e.ajax({
url:config.checkURL,
cache:false,
success:function(){
window.checknet.conIsActive=true
},
error:function(){
window.checknet.conIsActive=false
},
complete:function(){
if(window.checknet.conIsActive){
connectionExtablished()
}
else{
connectionLost()
}
}
})
setTimeout(
function(){checkConnection(config)},
config.checkInterval
)
}
}
})(jQuery);
I'm calling it every five seconds. When I shut down the server, Windows browsers do indeed notice within five seconds. However, the browsers on my Mac need about two and a half minutes.
From other questions, I gather that caching can be an issue. However, I've tried inserting parameters:"defeatcache=" + new Date().getTime() to the Ajax call and $.ajaxSetup({ cache: false }); before the Ajax call; neither works.
Does anybody have any suggestions for how I can get my Mac browsers to notice the downed connection sooner?

Answer 1

As mentioned in the comment and here How to disable Ajax caching in Safari browser?, you need to append the paramater to the URL, I'm not sure what this bit is doing parameters:"defeatcache=" but the way I have always used it is on the url:
url = url + '&nocache=' + new Date().getTime();
To modify your example where checkURL is the plain url unedited it should be
url:config.checkURL + '&nocache=' + new Date().getTime(),
If the above still does not work you want to add no-cache headers to the URL you are trying to access - for example if the url you were accessing was called "status.php" then you could try adding no-cached headers to the status.php page itself:
header('Cache-Control: no-cache, no-store, must-revalidate'); // HTTP 1.1.
header('Pragma: no-cache'); // HTTP 1.0.
Obviously this code above (for PHP) would be different depending on your sever side language (taken from & more examples for other server side languages here: einternals)

Answer 2

when you make your .ajax() call use the option cache: false
.ajax(
{url: 'http://...',
cache: false });
or
before your ajax call use ajaxSetup
$.ajaxSetup({ cache: false });

Answer 3

I used to disable caching in the response's header. So in the service that provides the response, look into setting various fields to disable caching from that end of the call. Sorry I don't have any ready examples!! Hope this helps.