query(e, 'effect')

Syntax

query(entity, 'effect', name)

Without extra arguments, it returns list of effect active on a living entity. Each entry is a triple of short effect name, amplifier, and remaining duration in ticks (-1 if it has infinity duration). With an argument, if the living entity has not that potion active, returns null, otherwise return a tuple of amplifier and remaining duration.

query(p,'effect')  => [[haste, 0, 177], [speed, 0, 177]]
query(p,'effect','haste')  => [0, 177]
query(p,'effect','resistance')  => null