The author of this quiz could have made this a great learning opportunity by linking to the appropriate sections in ECMA-262[0].

For example, question 15 makes a lot more sense when you read "ToBoolean" (Sec 9.2) which shows that all objects (including arrays) are always considered truthy values, however when compared with ==, "The Abstract Equality Comparison Algorithm" (11.9.3) is used, which gives this behavior:

  >> [0] == [0]
  false
  >> a = [0]; a == a
  true

because a shallow comparison is used.

[0] http://www.ecma-international.org/publications/files/ECMA-ST...