Some other weird things about falsy Javascript:
false == false
0 == false
[] == false
"" == false
"0" == false
"\t" == false
[] == false
["0"] == false
[[["0"]]] == false
[[[1 - 1]]] == false
[[[{}.foobar]]] == false
[[[`\t ${[].length} \t`]]] == false
// BUT
[false] != false