It's actually understandable, just tedious. Lot of dynamic typing/casting tricks. First, we set var '$' to bitwise NOT of [], which is -1 ([] casts to 0 or fal

It's actually understandable, just tedious. Lot of dynamic typing/casting tricks. First, we set var '$' to bitwise NOT of [], which is -1 ([] casts to 0 or false depending on the operator): $ = ~[]; Then we re-set $ to an object: $ = {___: ++$, $$$$: (![]+"")[$], ... Which gives us: $.___ == 0 // ($ was still -1, now it's 0) $.$$$$ == "f" // I think The "f" is a bit clever: ![] == false (![]+"") == "false" (![]+"")[$] is an index on the string, and $ is now 0 That's as far as I've bothered. (edited for formatting)