max
Parameters
value
Specifies how long results of a preflight request can be cached by a client in seconds. Note that many browser clients enforce a maximum TTL of 600s (10 minutes).
Setting the value to -1 forces a pre-flight check for all requests (not recommended)
A maximum TTL of 86400s can be set, but note that (as above) some clients may force pre-flight checks at a more regular interval.
This translates to the Access-Control-Max-Age header. A duration in seconds with up to nine fractional digits, terminated by 's'. Example: "3.5s".