What is the “right” JSON date format?

Question

I\'ve seen so many different standards for the JSON date format:

\"\\\"\\\\/Date(1335205592410)\\\\/\\\"\"         .NET JavaScriptSerializer
\"\\\"\\\\/Date(         


        

Answer 1

Just for reference I've seen this format used:

Date.UTC(2017,2,22)

It works with JSONP which is supported by the $.getJSON() function. Not sure I would go so far as to recommend this approach... just throwing it out there as a possibility because people are doing it this way.

FWIW: Never use seconds since epoch in a communication protocol, nor milliseconds since epoch, because these are fraught with danger thanks to the randomized implementation of leap seconds (you have no idea whether sender and receiver both properly implement UTC leap seconds).

Kind of a pet hate, but many people believe that UTC is just the new name for GMT -- wrong! If your system does not implement leap seconds then you are using GMT (often called UTC despite being incorrect). If you do fully implement leap seconds you really are using UTC. Future leap seconds cannot be known; they get published by the IERS as necessary and require constant updates. If you are running a system that attempts to implement leap seconds but contains and out-of-date reference table (more common than you might think) then you have neither GMT, nor UTC, you have a wonky system pretending to be UTC.

These date counters are only compatible when expressed in a broken down format (y, m, d, etc). They are NEVER compatible in an epoch format. Keep that in mind.