Sorry but this will not help you learn JavaScript.
I am sure it will help you remember built-ins and terminology, but using PLs is far more than a human memory game, I know JS pretty thoroughly and cannot recall every Math or Array method, it's just not very important. If you want to get better at any PL, write it, write it, write it.
If you don't know what to write, I'd recommend heading over to somewhere like rossetacode and picking an unimplemented problem you like the look of.
I am sure it will help you remember built-ins and terminology, but using PLs is far more than a human memory game, I know JS pretty thoroughly and cannot recall every Math or Array method, it's just not very important. If you want to get better at any PL, write it, write it, write it.
If you don't know what to write, I'd recommend heading over to somewhere like rossetacode and picking an unimplemented problem you like the look of.