Javascript developer needed for "latency" testing

I'm looking for a capable Javascript developer that can put together something for me to test the "ping" of a server/endpoint and show the data with the details required. Whilst I'm aware there is no "ping" in Javascript itself and understand that the results won't be the same as an actual PING request by a device, I'm looking to get as close as possible (and consistent as possible, removing any inconsistencies from our end) so that it's a somewhat real-world view. Tests will range from a single endpoint to 50-75 so this should be able to handle that and "scale" the number of tests as needed. We may want to look at limiting the number that run at one time to prevent overloading the browser. Please tell me your initial ideas and thoughts on implementing this and provide examples of RELEVANT work (if you have it, if not, please provide examples of previous Javascript/frontend work) in your proposal so I can see that you've read this and not simply copied and pasted the same text you use for everyone else. Thanks!