MooTools Depender, Safari, etags and 412 Precondition Failed

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/**
* This replaces the default MooTools more Depender.request function to use
* HTTP "get" rather than "post".
*
* When sending requests for files via the depender, I was finding that Safari
* wasn't getting and re-evaluating them the second time I visited the page.
* This was because an etag was sent with each script.
*
* Safari responds to etags properly and adds "If-None-Match" and
* "If-Modified-Since" headers to another request for the same file. This makes
* Apache respond with a 412 status (Precondition Failed) as it should do for
* "post" requests (according to RFC 2616).
*
* Unfortunately Safari doesn't then deal with the 412 as it does with a 304
* (Not Modified). It doesn't grab what it has in the cache and put it in the
* response, it gives you nothing.
*
* For "get" requests, Apache has to respond with a 304, or 200 or whatever, but
* not 412. So we change the request method so we don't have to deal with 412.
*/
Depender.request = function(url, callback){
    new Request.JSON({
        url: url,
        secure: false,
        onSuccess: callback,
        method:'get'
    }).send();
};

24,935 thoughts on “MooTools Depender, Safari, etags and 412 Precondition Failed”

  2. Spot on with this write-up, I honestly believe that this
    website needs a great deal more attention. I’ll probably be back
    again to read through more, thanks for the advice!