Measure and Display Network Latency from Client to LTM

I know this is an old and tired topic, but I' like to revive it. I have a need to display an approximate network latency to a web page which is rendered by an iRule. My company has data centers on several continents, and we have a web page that an F5 iRule displays which is a simple "Hi, you've reach the xyz datacenter", it would be nice if I could display on that page how long the latency was to get to that data center, from wherever that client is sitting. Understand that Javascript date values aren't all that accurate, and that the time has to be measured at the client to be accurate, but even the results of a simple ping from the F5 back to the client's IP address (doesn't have to be automatic: could be a button 'press here to measure your round trip time to THIS datacenter' would suffice). The key is, if I had this on a similar page in each of our datacenters, our customers could see the "RELATIVE" difference between hitting say, Singapore, verses, Calgary, if they visit each datacenter and run the test for themselves. - Turning on analytics within the LTM doesn't help, as it's not my company's engineers who need the results: we want to display it back to the client.