Is Safari on iOS 6 caching $.ajax results?

Question

Since the upgrade to iOS 6, we are seeing Safari\'s web view take the liberty of caching $.ajax calls. This is in the context of a PhoneGap application so it is

Answer 1

We found that older iPhones and iPads, running iOS versions 9 & 10, occasionally return bogus blank AJAX results, perhaps due to Apple's turning down CPU speed. When returning the blank result, iOS does not call the server, as if returning a result from cache. Frequency varies widely, from roughly 10% to 30% of AJAX calls return blank.

The solution is hard to believe. Just wait 1s and call again. In our testing, only one repeat was all that was ever needed, but we wrote the code to call up to 4 times. We're not sure if the 1s wait is required, but we didn't want to risk burdening our server with bursts of repeated calls.

We found the problem happened with two different AJAX calls, calling on different API files with different data. But I'm concerned it could happen on any AJAX call. We just don't know because we don't inspect every AJAX result and we don't test every call multiple times on old devices.

Both problem AJAX calls were using: POST, Asynchronously = true, setRequestHeader = ('Content-Type', 'application/x-www-form-urlencoded')

When the problem happens, there's usually only one AJAX call going on. So it's not due to overlapping AJAX calls. Sometimes the problem happens when the device is busy, but sometimes not, and without DevTools we don't really know what's happening at the time.

iOS 13 doesn't do this, nor Chrome or Firefox. We don't have any test devices running iOS 11 or 12. Perhaps someone else could test those?

I'm noting this here because this question is the top Google result when searching for this problem.