JavaScript: Objects and Arrays Quiz

JavaScript: Objects and Arrays Quiz

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JavaScript: Objects and Arrays Quiz

?: Given a number of elements that need to stay in order, would you use an Object or an Array?

( ) Object (x) Array

?: Given a collection of artists and lists of their songs, would you store the artist-song-list pairs in an Object or an Array?

(x) Object ( ) Array

?: True or false: All the elements in an array must be of the same type.

( ) True (x) False

?: True or false: All keys in an object are strings.

(x) True ( ) False

?: What happens to the array in the following code snippet?

const dogs = ["Fido", "Odie", "Oscar"]

dogs.length

dogs.length = 1

( ) Nothing ( ) The array becomes just ["Oscar"] (x) The array becomes just ["Fido"] ( ) The array becomes just ["Odie", "Oscar"]

?: What are the keys in the object after running the code below?

const artistsAndSongs = {
  'Prince': ["Purple Rain", "When Doves Cry"],
  'The Beatles': ["Revolution", "Norwegian Wood"],
  'Joni Mitchell': ["A Case of You", "Sunny Sunday"],
  'Justin Bieber': ["Baby"]
}

artistsAndSongs['Daft Punk'] = ["Harder, Better, Faster, Stronger"]

delete artistsAndSongs["Justin Bieber"]

( ) ['Prince', 'The Beatles', 'Joni Mitchell', 'Justin Bieber', 'Daft Punk'] ( ) ['Prince', 'The Beatles', 'Joni Mitchell', 'Justin Bieber'] ( ) ['Prince', 'The Beatles', 'Joni Mitchell'] (x) ['Prince', 'The Beatles', 'Joni Mitchell', 'Daft Punk']

?: If we run artistsAndSongs['Daft Punk'].push("Around the World") after running the code below, what is the value of the object?

const artistsAndSongs = {
  'Prince': ["Purple Rain", "When Doves Cry"],
  'The Beatles': ["Revolution", "Norwegian Wood"],
  'Joni Mitchell': ["A Case of You", "Sunny Sunday"],
  'Justin Bieber': ["Baby"]
}

artistsAndSongs['Daft Punk'] = ["Harder, Better, Faster, Stronger"]

delete artistsAndSongs["Justin Bieber"]

( )

const artistsAndSongs = {
  'Prince': ["Purple Rain", "When Doves Cry"],
  'The Beatles': ["Revolution", "Norwegian Wood"],
  'Joni Mitchell': ["A Case of You", "Sunny Sunday"],
  'Daft Punk': ["Harder, Better, Faster, Stronger"]
}

(x)

const artistsAndSongs = {
  'Prince': ["Purple Rain", "When Doves Cry"],
  'The Beatles': ["Revolution", "Norwegian Wood"],
  'Joni Mitchell': ["A Case of You", "Sunny Sunday"],
  'Daft Punk': ["Harder, Better, Faster, Stronger", "Around the World"]
}

( )

const artistsAndSongs = {
  'Prince': ["Purple Rain", "When Doves Cry"],
  'The Beatles': ["Revolution", "Norwegian Wood"],
  'Joni Mitchell': ["A Case of You", "Sunny Sunday"],
  'Daft Punk': ["Around the World"]
}

( )

const artistsAndSongs = {
  'Prince': ["Purple Rain", "When Doves Cry"],
  'The Beatles': ["Revolution", "Norwegian Wood"],
  'Joni Mitchell': ["A Case of You", "Sunny Sunday"]
}

?: What is the result of the following code in a browser that supports the spread operator?

const oneTwoThree = [1, 2, 3]
const sevenEightNine = [7, 8, 9]

const result = [4, 5, 6, ...oneTwoThree, ...sevenEightNine]

( ) [4, 5, 6, 7, 8, 9, 1, 2, 3] (x) [4, 5, 6, 1, 2, 3, 7, 8, 9] ( ) [1, 2, 3, 4, 5, 6, 7, 8, 9] ( ) Error

?: Given the array const letters = ["alpha", "gamma", "delta"], which operation(s) return the array ["alpha", "beta", "gamma", "delta"] without mutating (changing) the letters Array?

( ) letters.push("beta") ( ) letters.unshift('beta') (x) [...letters.slice(0, 1), 'beta', ...letters.slice(1)] ( ) letters.splice(1, 1, 'beta') ( ) letters.splice(1, 0, 'beta')

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