Arrow functions

Arrow functions added in ES6 provide a good replacement for function expressions. But do you understand them completely? This is a small test to check it out.

Total questions • 22

```
(_ => _)(99)
```
99

error

null

undefined

((x=>{})(),(x=>x=>x)())(()=>true)(false)

false

true

```
null => null
```
Error

null

null => null

null => undefined
```
null, undefined => null
```
Error

undefined

null

undefined => null
```
(({})({}))
```
Error

{}

null

undefined
```
(() => {x:1})()
```
Error

{x:1}

null

undefined
```
(() => ({x:1}))()
```
Error

{x:1}

null

undefined
```
(() => arguments)(99)
```
Error

99

arguments

undefined
```
((x,y,z) => (1,2,3))(4,5,6)
```
Error

6

3

1,2,3
```
() => () => () => {}
```
Error

() => () => () => {}

() => {}

undefined
```
() => {} == () => {}
```
Error

() => {} == () => {}

{}

undefined
```
(() => { return this;})()
```
Error

this

window

undefined
```
() => ()
```
Error

() => ()

function() {}

fn
```
(() => {return})()
```
Error

0

""

undefined
```
x => false()
```
Error

x => false()

false

0
```
(() => [()=>(1)])()[0]()
```
Error

0

1

()=>(1)
```
(let => let)('Really?')
```
Error

Really?

undefined

false
```
(const => const)('Really again?')
```
Error

Really again?

undefined

false
```
var y = (var) => {var}
```
Error

undefined

null

false
```
`${() => 3}`
```
Error

() => 3

3

undefined
```
(() => Function()())()
```
Error

undefined

null

()
```
typeof ()=>{}
```
Error

function

string

undefined

Correct answers :

Incorrect answers :

Unanswered :

For all explanations to above question please see the article