10

20

30

40

undefined

12 14

false

null

true

1 2 3

{ a: 1, b: 2, c: 3 }

[1, 2, 3]

undefined undefined undefined

ReferenceError

20

NaN

undefined

20

-20

21

-21

undefined

1 undefined 2 undefined 3 undefined 4 undefined

1 2 3 3 6 4

1 2 undefined 3 undefined 4

1 2 2 3 3 4

undefined

Error

Brendan

null

Hello World

TypeError

undefined

ReferenceError

"global" "outer-2" "inner"

"global" "outer" "inner"

"guess" "outer" "inner"

"guess" "outer-2" "inner"

Lydia

myName

ReferenceError

undefined