JavaScript Quiz 01


What do the following lines print to the console?

console.log([1,2,3].toString())

a) 1, 2, 3

b) [1, 2, 3]

c) 1 2 3

d) 1\n2\n3

e) undefined

f) error

console.log(true.toString())

a) 1

b) true

c) 0

d) true.toString()

e) undefined

f) error

console.log(2.toString())

a) 2

b) 2.0

c) two

d) 1.999999

e) undefined

f) error

console.log(2..toString())

a) 2

b) 2.0

c) two

d) 1.999999

e) undefined

f) error


What do the following lines print after this code is run:

var a = {
    name: "Eric", "phone": "555-555-5555",
    address: "2121 S Mill Ave"
}

console.log(a.name)

a) name: "Eric"

b) { name: "Eric", phone: "555-555-5555", address: "2121 S Mill Ave" }

c) Eric

d) undefined

e) error

console.log(a..name)

a) name: "Eric"

b) { name: "Eric", phone: "555-555-5555", address: "2121 S Mill Ave" }

c) Eric

d) undefined

e) error

console.log(a[name])

a) name: "Eric"

b) { name: "Eric", phone: "555-555-5555", address: "2121 S Mill Ave" }

c) Eric

d) undefined

e) error

console.log(a['name'])

a) name: "Eric"

b) { name: "Eric", phone: "555-555-5555", address: "2121 S Mill Ave" }

c) Eric

d) undefined

e) error

console.log(a.phone)

a) phone: "555-555-5555"

b) { name: "Eric", phone: "555-555-5555", address: "2121 S Mill Ave" }

c) "555-555-5555"

d) undefined

e) error

console.log(a['phone'])

a) phone: "555-555-5555"

b) { name: "Eric", phone: "555-555-5555", address: "2121 S Mill Ave" }

c) "555-555-5555"

d) undefined

e) error

console.log(a["phone"])

a) phone: "555-555-5555"

b) { name: "Eric", phone: "555-555-5555", address: "2121 S Mill Ave" }

c) "555-555-5555"

d) undefined

e) error


What do the following lines print after this code is run:

var animal = { speak: function() { console.log(this.sound) } };

function Cow() { this.sound = 'moo'; }
function Duck() { this.sound = 'quack'; }
function Horse() { this.sound = 'neigh'; }
Cow.prototype = animal;
Duck.prototype = animal;

animal.speak()

a) moo

b) quack

c) neigh

d) undefined

f) nothing

e) error

Cow.speak()

a) moo

b) quack

c) neigh

d) undefined

f) nothing

e) error

c = new Cow(); c.speak()

a) moo

b) quack

c) neigh

d) undefined

f) nothing

e) error

new Duck().speak()

a) moo

b) quack

c) neigh

d) undefined

f) nothing

e) error

h = new Horse(); h.speak()

a) moo

b) quack

c) neigh

d) undefined

f) nothing

e) error

confused = new Cow(); confused.sound = 'neigh'; confused.speak()

a) moo

b) quack

c) neigh

d) undefined

f) nothing

e) error

c = new Cow(); console.log(c instanceof animal);

a) true

b) false

c) undefined

d) error

c = new Cow(); console.log(c instanceof Cow());

a) true

b) false

c) undefined

d) error

c = new Cow(); console.log(c instanceof Cow);

a) true

b) false

c) undefined

d) error

confused = new Cow(); confused.sound = 'neigh'; console.log(confused instanceof Cow);

a) true

b) false

c) undefined

d) error

c = new Cow(); for(var prop in c) { console.log(prop); }

a) speak

b) sound

c) speak\nsound

d) nothing

e) undefined

f) error

c = new Cow(); console.log(typeof c);

a) number

b) boolean

c) function

d) undefined

e) object

console.log(typeof Cow);

a) number

b) boolean

c) function

d) undefined

e) object

console.log(typeof Cow());

a) number

b) boolean

c) function

d) undefined

e) object

console.log(typeof new Cow());

a) number

b) boolean

c) function

d) undefined

e) object

console.log(typeof animal);

a) number

b) boolean

c) function

d) undefined

e) object


What do the following code blocks print?

function raiseSails() { console.log('sails raised'); }
raiseSails();

a) sails raised\nsails raised

b) sails raised

c) nothing

d) undefined

f) error

raiseSails();
function raiseSails() { console.log('sails raised'); }

a) sails raised\nsails raised

b) sails raised

c) nothing

d) undefined

f) error

var raiseSails = function() { console.log('sails raised'); };
raiseSails();

a) sails raised\nsails raised

b) sails raised

c) nothing

d) undefined

f) error

raiseSails();
var raiseSails = function() { console.log('sails raised'); };

a) sails raised\nsails raised

b) sails raised

c) nothing

d) undefined

f) error


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