I would like to test the content download speed, how fast was the first byte transferred, the size of the content being requested, full-load time, document complete time and other in-depth characteristics that could really be tested.
What can I think of is sending an AJAX request to download the given resource from the CDN and the time the AJAX request is completed will be the content downloaded time. I am not really sure how accurate would the result be.
What about the other characteristics?
Are there any tools/libraries built for this? Accuracy is vast importance for the tests.