_ is a variable name, [] becomes 0 when converted to an integer, !![] becomes 1. The + “” + means that the integers 1, 0, 0 get converted to a string - “100”, which gets converted back to an integer because it’s in the for loop. And there’s various other horrible conversions going on to make it all work.
Or this one without the “undefined” when run in a browser console:
for(_=[];_<+!![]+""+[]*[]+[]*[]-!![]-!![];_++%+(!![]+!![])?[]:console.log(_));_+!![]Wtf people, can somebody explain?
_ is a variable name, [] becomes 0 when converted to an integer, !![] becomes 1. The + “” + means that the integers 1, 0, 0 get converted to a string - “100”, which gets converted back to an integer because it’s in the for loop. And there’s various other horrible conversions going on to make it all work.