javascript - Working vs an old project and find code which I don't understand -

i don't understand following code please explain me
sorry might seem weird, gotta understand

reverse = [-1, 1][+!!reverse]; 

let's reverse = 5, !5 false since every number except 0 thruty, if negate again !false obtain true , convert our boolean expression either 1 or 0 using +.

var reverse = 5; reverse = [-1, 1][+!!reverse]; 

is same as

var reverse = 5; reverse = [-1, 1][1]; 

to more explicit have been:

var reverse = 5; reverse = [-1, 1][number(boolean(reverse))];