What's the difference in browser behavior between two headers Cache-control: max-age=0 and Cache-control: max-age=-1?
If the browser receives max-age=0, it will revalidate cache immediately. If the browser receives max-age=10, it will revalidate cache after 10 seconds. What's browser behavior with max-age=-1? Is it the same like with max-age=0? If yes, why we need both?
max-age takes an argument that matches delta-seconds:
The delta-seconds rule specifies a non-negative integer, representing
time in seconds.
delta-seconds = 1*DIGIT
max-age=-1 is therefore not a valid directive, and the specification doesn't define an interpretation. The spec suggests:
Caches are
encouraged to consider responses that have invalid freshness
information to be stale.