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

I believe that the best format for universal interoperability is not the ISO-8601 string, but rather the format used by EJSON:

{ "myDateField": { "$date" : } }

As described here: https://docs.meteor.com/api/ejson.html

Benefits

1. Parsing performance: If you store dates as ISO-8601 strings, this is great if you are expecting a date value under that particular field, but if you have a system which must determine value types without context, you're parsing every string for a date format.
2. No Need for Date Validation: You need not worry about validation and verification of the date. Even if a string matches ISO-8601 format, it may not be a real date; this can never happen with an EJSON date.
3. Unambiguous Type Declaration: as far as generic data systems go, if you wanted to store an ISO string as a string in one case, and a real system date in another, generic systems adopting the ISO-8601 string format will not allow this, mechanically (without escape tricks or similar awful solutions).

Conclusion

I understand that a human-readable format (ISO-8601 string) is helpful and more convenient for 80% of use cases, and indeed no-one should ever be told not to store their dates as ISO-8601 strings if that's what their applications understand, but for a universally accepted transport format which should guarantee certain values to for sure be dates, how can we allow for ambiguity and need for so much validation?