Objects and loops: Live coding ​

// arrays.js
// Top five UK singles of the 1980s
const songs = [
  "Do They Know It's Christmas?",
  "Relax",
  "I Just Called to Say I Love You",
  "Two Tribes",
  "Don't You Want Me",
]

console.log('The fifth song:')
console.log(songs[4])

console.log('Adding a song to the end of the list:')
songs.push("Last Christmas")
console.log(songs.slice(-1))

console.log('How many characters are in each song:')
for (const song of songs) {
  console.log(song.length)
}

console.log('Songs with "You":')
for (const song of songs) {
  if (song.includes('You')) {
    console.log(song)
  }
}

console.log('A list of all the unique words in the songs:')
const uniqueWords = []
for (const song of songs) {
  const wordsInSong = song.split(' ')
  for (const word of wordsInSong) {
    if (!uniqueWords.includes(word)) {
      uniqueWords.push(word)
    }
  }
}
console.log(uniqueWords)

console.log('The word list, sorted alphabetically:')
console.log(uniqueWords.sort())

console.log('Each song title, lowercase, with no punctuation:')
const charactersToKeep = ' abcdefghijklmnopqrstuvwxyz'
for (const song of songs) {
  let lowercaseSong = ''
  for (const character of song) {
    const lowercaseCharacter = character.toLowerCase()
    if (charactersToKeep.includes(lowercaseCharacter)) {
      lowercaseSong = lowercaseSong + lowercaseCharacter
    }
  }
  console.log(lowercaseSong)
}

// arrays.js
// Top five UK singles of the 1980s
const songs = [
  "Do They Know It's Christmas?",
  "Relax",
  "I Just Called to Say I Love You",
  "Two Tribes",
  "Don't You Want Me",
]

console.log('The fifth song:')
console.log(songs[4])

console.log('Adding a song to the end of the list:')
songs.push("Last Christmas")
console.log(songs.slice(-1))

console.log('How many characters are in each song:')
for (const song of songs) {
  console.log(song.length)
}

console.log('Songs with "You":')
for (const song of songs) {
  if (song.includes('You')) {
    console.log(song)
  }
}

console.log('A list of all the unique words in the songs:')
const uniqueWords = []
for (const song of songs) {
  const wordsInSong = song.split(' ')
  for (const word of wordsInSong) {
    if (!uniqueWords.includes(word)) {
      uniqueWords.push(word)
    }
  }
}
console.log(uniqueWords)

console.log('The word list, sorted alphabetically:')
console.log(uniqueWords.sort())

console.log('Each song title, lowercase, with no punctuation:')
const charactersToKeep = ' abcdefghijklmnopqrstuvwxyz'
for (const song of songs) {
  let lowercaseSong = ''
  for (const character of song) {
    const lowercaseCharacter = character.toLowerCase()
    if (charactersToKeep.includes(lowercaseCharacter)) {
      lowercaseSong = lowercaseSong + lowercaseCharacter
    }
  }
  console.log(lowercaseSong)
}

// objects.js
// Top two singles from the UK in 1980s
const dontTheyKnow = {
  rank: 1,
  title: "Do They Know It's Christmas?",
  year: 1984
}

const lastChristmas = {
  rank: 2,
  title: "Relax",
  year: 1983
}

console.log('The song titles:')
console.log(dontTheyKnow.title)
console.log(lastChristmas.title)

console.log('Adding an artist for each song:')
dontTheyKnow.artist = 'Band Aid'
lastChristmas.artist = 'Frankie Goes to Hollywood'

console.log('Switching the rank:')
dontTheyKnow.rank = 2
lastChristmas.rank = 1

console.log('They are from the same year:')
console.log(dontTheyKnow.year === lastChristmas.year)

console.log("All the data about the Don't They Know It's Christmas:")
for (const property in dontTheyKnow) {
  const value = dontTheyKnow[property]
  console.log(`${key}: ${value}`)
}

console.log('An array of the song objects:')
const songs = [dontTheyKnow, lastChristmas]
console.log(songs)

console.log('The title of the second song:')
console.log(songs[1].title)

console.log('The artist of the first song:')
console.log(songs[0].artist)

console.log('Now the titles and artists are uppercase:')
for (const song of songs) {
  song.title = song.title.toUpperCase()
  song.artist = song.artist.toUpperCase()
}
console.log(songs)

console.log('Another song to add to the song array:')
const twoTribes = {
  "rank": 4,
  "title": "TWO TRIBES",
  "artist": "FRANKIE GOES TO HOLLYWOOD",
  "year": 1984
}
songs.push(twoTribes)
console.log(twoTribes)

console.log(`Using loops to build a new object
that records how many top songs each artist has:`)
const numberOfTopSongs = {}
for (const song of songs) {
  const artist = song.artist
  if (!numberOfTopSongs.hasOwnProperty(artist)) {
    numberOfTopSongs[artist] = 1
  } else {
    numberOfTopSongs[artist] = numberOfTopSongs[artist] + 1
  }
}
console.log(numberOfTopSongs)

// objects.js
// Top two singles from the UK in 1980s
const dontTheyKnow = {
  rank: 1,
  title: "Do They Know It's Christmas?",
  year: 1984
}

const lastChristmas = {
  rank: 2,
  title: "Relax",
  year: 1983
}

console.log('The song titles:')
console.log(dontTheyKnow.title)
console.log(lastChristmas.title)

console.log('Adding an artist for each song:')
dontTheyKnow.artist = 'Band Aid'
lastChristmas.artist = 'Frankie Goes to Hollywood'

console.log('Switching the rank:')
dontTheyKnow.rank = 2
lastChristmas.rank = 1

console.log('They are from the same year:')
console.log(dontTheyKnow.year === lastChristmas.year)

console.log("All the data about the Don't They Know It's Christmas:")
for (const property in dontTheyKnow) {
  const value = dontTheyKnow[property]
  console.log(`${key}: ${value}`)
}

console.log('An array of the song objects:')
const songs = [dontTheyKnow, lastChristmas]
console.log(songs)

console.log('The title of the second song:')
console.log(songs[1].title)

console.log('The artist of the first song:')
console.log(songs[0].artist)

console.log('Now the titles and artists are uppercase:')
for (const song of songs) {
  song.title = song.title.toUpperCase()
  song.artist = song.artist.toUpperCase()
}
console.log(songs)

console.log('Another song to add to the song array:')
const twoTribes = {
  "rank": 4,
  "title": "TWO TRIBES",
  "artist": "FRANKIE GOES TO HOLLYWOOD",
  "year": 1984
}
songs.push(twoTribes)
console.log(twoTribes)

console.log(`Using loops to build a new object
that records how many top songs each artist has:`)
const numberOfTopSongs = {}
for (const song of songs) {
  const artist = song.artist
  if (!numberOfTopSongs.hasOwnProperty(artist)) {
    numberOfTopSongs[artist] = 1
  } else {
    numberOfTopSongs[artist] = numberOfTopSongs[artist] + 1
  }
}
console.log(numberOfTopSongs)

// from.js
export const song = 'Eye of the Tiger'

const anotherSong = 'Last Christmas'
// console.log(anotherSong)

// from.js
export const song = 'Eye of the Tiger'

const anotherSong = 'Last Christmas'
// console.log(anotherSong)

// to.js
import { song } from './from.js'
console.log(song)

// import { anotherSong } from './from.js'
// Will raise error because anotherSong is not exported

// to.js
import { song } from './from.js'
console.log(song)

// import { anotherSong } from './from.js'
// Will raise error because anotherSong is not exported