Passo 30

Instruções

Crie uma função chamada playPreviousSong. Dentro da sua nova função, use o valor retornado pela função getPreviousSong para encontrar a música a ser reproduzida. Quando getPreviousSong() estiver undefined, toque a primeira música da sua playlist. Caso contrário, toque a música antes da música atual que está tocando.

O que fazer:

Testes:

Você deve ter uma função chamada `playPreviousSong`.
A função `playPreviousSong` deve tocar a música anterior à música atual que está tocando na playlist.
Quando `getPreviousSong()` está `undefined`, a função `playPreviousSong` deve tocar a primeira música na playlist.

<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8" />
  <meta name="viewport" content="width=device-width, initial-scale=1.0" />
  <link href="https://fonts.googleapis.com/css2?family=Roboto+Mono&display=swap" rel="stylesheet" />
  <link href="https://fonts.googleapis.com/css2?family=Lato&family=Roboto+Mono&display=swap" rel="stylesheet" />
  <link rel="stylesheet" href="styles.css" />
  <title>
    Build a Music Player App
  </title>
</head>

<body>
  <div class="container">
    <div class="player">
      <div class="player-bar">
        <div class="parallel-lines">
          <div></div>
          <div></div>
        </div>
        <h1 class="fcc-title">G.E.A.R ACADEMY</h1>
        <div class="parallel-lines">
          <div></div>
          <div></div>
        </div>
      </div>
      <div class="player-content">
        <div id="player-album-art">
          <img src="https://cdn.G.E.A.R ACADEMY.org/curriculum/js-music-player/quincy-larson-album-art.jpg"
            alt="song cover art" />
        </div>
        <div class="player-display">
          <div class="player-display-song-artist">
            <p id="player-song-title"></p>
            <p id="player-song-artist"></p>
          </div>
          <div class="player-buttons">
            <button id="previous" class="previous" aria-label="Previous">
              <svg width="24" height="19" viewBox="0 0 24 19" fill="none" xmlns="http://www.w3.org/2000/svg">
                <path d="M23.2248 0L7.03964 9.5L23.2248 19L23.2248 0Z" />
                <rect width="4.63633" height="18.5453" transform="matrix(-1 0 0 1 4.63633 0)" />
              </svg>
            </button>
            <button id="play" class="play" aria-label="Play">
              <svg width="17" height="19" viewBox="0 0 17 19" fill="none" xmlns="http://www.w3.org/2000/svg">
                <path d="M0 0L16.1852 9.5L1.88952e-07 19L0 0Z" />
              </svg>
            </button>
            <button id="pause" class="pause" aria-label="Pause">
              <svg width="17" height="19" viewBox="0 0 17 19" fill="none" xmlns="http://www.w3.org/2000/svg">
                <path d="M0 6.54013e-07H4.75V19H0V6.54013e-07Z" />
                <path d="M11.4 0H16.15V19H11.4V0Z" />
              </svg>
            </button>
            <button id="next" class="next" aria-label="Next">
              <svg width="24" height="19" viewBox="0 0 24 19" fill="none" xmlns="http://www.w3.org/2000/svg">
                <path d="M0 0L16.1852 9.5L1.88952e-07 19L0 0Z" />
                <rect x="18.5885" width="4.63633" height="18.5453" />
              </svg>
            </button>
          </div>
        </div>
      </div>
    </div>
    <div class="playlist">
      <div class="playlist-bar">
        <div class="parallel-lines">
          <div></div>
          <div></div>
        </div>
        <h2 class="playlist-title" id="playlist">Playlist</h2>
        <div class="parallel-lines">
          <div></div>
          <div></div>
        </div>
      </div>
      <ul id="playlist-songs">
        <li id="song-0" class="playlist-song">
          <button class="playlist-song-info" >
            <span class="playlist-song-title">Scratching The Surface</span>
            <span class="playlist-song-artist">Quincy Larson</span>
            <span class="playlist-song-duration">4:25</span>
          </button>
        </li>

        <li id="song-1" class="playlist-song">
          <button class="playlist-song-info" >
            <span class="playlist-song-title">Can't Stay Down</span>
            <span class="playlist-song-artist">Quincy Larson</span>
            <span class="playlist-song-duration">4:15</span>
          </button>
        </li>

        <li id="song-2" class="playlist-song">
          <button class="playlist-song-info" >
            <span class="playlist-song-title">Still Learning</span>
            <span class="playlist-song-artist">Quincy Larson</span>
            <span class="playlist-song-duration">3:51</span>
          </button>
        </li>

        <li id="song-3" class="playlist-song">
          <button class="playlist-song-info" >
            <span class="playlist-song-title">Cruising for a Musing</span>
            <span class="playlist-song-artist">Quincy Larson</span>
            <span class="playlist-song-duration">3:34</span>
          </button>
        </li>

        <li id="song-4" class="playlist-song">
          <button class="playlist-song-info" >
            <span class="playlist-song-title">Never Not Favored</span>
            <span class="playlist-song-artist">Quincy Larson</span>
            <span class="playlist-song-duration">3:35</span>
          </button>
        </li>

        <li id="song-5" class="playlist-song">
          <button class="playlist-song-info" >
            <span class="playlist-song-title">From the Ground Up</span>
            <span class="playlist-song-artist">Quincy Larson</span>
            <span class="playlist-song-duration">3:12</span>
          </button>
        </li>

        <li id="song-6" class="playlist-song">
          <button class="playlist-song-info" >
            <span class="playlist-song-title">Walking on Air</span>
            <span class="playlist-song-artist">Quincy Larson</span>
            <span class="playlist-song-duration">3:25</span>
          </button>
        </li>

        <li id="song-7" class="playlist-song">
          <button class="playlist-song-info" >
            <span class="playlist-song-title">Can't Stop Me. Can't Even Slow Me Down.</span>
            <span class="playlist-song-artist">Quincy Larson</span>
            <span class="playlist-song-duration">3:52</span>
          </button>
        </li>

        <li id="song-8" class="playlist-song">
          <button class="playlist-song-info" >
            <span class="playlist-song-title">The Surest Way Out is Through</span>
            <span class="playlist-song-artist">Quincy Larson</span>
            <span class="playlist-song-duration">3:10</span>
          </button>
        </li>

        <li id="song-9" class="playlist-song">
          <button class="playlist-song-info" >
            <span class="playlist-song-title">Chasing That Feeling</span>
            <span class="playlist-song-artist">Quincy Larson</span>
            <span class="playlist-song-duration">2:43</span>
          </button>
        </li>
      </ul>
    </div>
  </div>
  <script src="script.js"></script>
</body>

</html>

:root {
    /* colors */
    --primary-color: #dfdfe2;
    --secondary-color: #ffffff;
    --app-background-color: #4d4d62;
    --background-color: #1b1b32;
    --foreground-color: #3b3b4f;
    --highlight-color: #f1be32;

    /* font sizes */
    --root-font-size: 16px;
    font-size: var(--root-font-size);

    /* font-families */
    --font-headline: "Roboto Mono", monospace;
    --font-family: "Lato", sans-serif;
  }

  *,
  *::after,
  *::before {
    box-sizing: border-box;
  }

  body {
    background-color: var(--app-background-color);
    color: var(--primary-color);
    font-family: var(--font-family);
  }

  h1 {
    font-size: 1.125rem;
    line-height: 1.6;
  }

  h2 {
    font-size: var(--root-font-size);
  }

  ul {
    margin: 0;
  }

  .container {
    margin-top: 10px;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    row-gap: 5px;
  }

  .player,
  .playlist {
    width: 450px;
    background-color: var(--background-color);
    border: 3px solid var(--foreground-color);
  }

  .player {
    height: 260px;
    padding: 10px;
    display: flex;
    flex-direction: column;
    align-items: center;
    row-gap: 10px;
  }

  .player-bar,
  .playlist-bar {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 0 5px;
    width: 100%;
    height: 30px;
    background-color: var(--foreground-color);
  }

  .parallel-lines {
    display: flex;
    flex-wrap: wrap;
    row-gap: 6px;
    padding: 0 5px;
  }

  .parallel-lines > div {
    height: 2px;
    width: 100%;
    min-width: 75px;
    background-color: var(--highlight-color);
  }

  .fcc-title,
  .playlist-title {
    color: var(--secondary-color);
    margin: 0 10px;
    font-family: var(--font-headline);
  }

  .player-content {
    display: flex;
    background-color: var(--foreground-color);
    width: 430px;
    height: 200px;
    column-gap: 13px;
    align-items: center;
    justify-content: center;
  }

  #player-album-art {
    background-color: var(--secondary-color);
    border: 6px solid var(--background-color);
  }

  #player-album-art img {
    width: 150px;
    display: block;
  }

  .player-display {
    display: flex;
    flex-direction: column;
    row-gap: 20px;
    padding: 14px;
    background-color: var(--background-color);
    height: 153px;
    width: 226px;
  }

  .player-display-song-artist {
    height: 80px;
  }

  .player-buttons svg {
    fill: var(--primary-color);
  }

  .playing > svg {
    fill: var(--highlight-color);
  }

  .player-buttons {
    display: flex;
    justify-content: space-around;
  }

  button {
    background: transparent;
    border: none;
    color: var(--primary-color);
    cursor: pointer;
    font-size: var(--root-font-size);
    outline-color: var(--highlight-color);
    text-align: center;
  }

  .playlist-song {
    outline-color: var(--highlight-color);
  }

  .playlist li:not(:last-child) {
    border-bottom: 1px solid var(--background-color);
  }

  button:focus,
  .playlist-song:focus {
    outline-style: dashed;
    outline-width: 2px;
  }

  /* Playlist */
  .playlist {
    height: auto;
    padding: 10px;
    display: flex;
    flex-direction: column;
    align-items: center;
    row-gap: 10px;
  }

  #playlist-songs {
    width: 430px;
    height: 100%;
    background-color: var(--foreground-color);
    display: flex;
    flex-direction: column;
    row-gap: 8px;
    padding: 8px 9px;
    visibility: visible;
    justify-content: start;
    list-style: none;
  }

  .playlist-song {
    display: flex;
    height: 55px;
    justify-content: space-between;
    align-items: center;
    padding: 5px;
  }

  [aria-current="true"] {
    background-color: var(--background-color);
  }

  [aria-current="true"] p {
    color: var(--highlight-color);
  }

  .playlist-song-info {
    height: 100%;
    display: flex;
    flex-direction: row;
    align-items: center;
    justify-content: space-around;
    column-gap: 7px;
    padding: 5px 0;
    font-family: var(--font-family);
  }

  #player-song-title,
  #player-song-artist {
    margin: 0;
  }

  #player-song-artist {
    color: var(--highlight-color);
    font-size: 0.75rem;
  }

  #player-song-title {
    font-size: 1.125rem;
  }

  .playlist-song-title {
    font-size: 0.85rem;
    width: 241px;
    text-align: left;
  }

  .playlist-song-artist {
    font-size: 0.725rem;
    width: 80px;
  }

  .playlist-song-duration {
    font-size: 0.725rem;
    margin: auto;
    font-family: var(--font-headline);
    width: 30px;
  }

  .playlist-song-delete {
    padding: 0;
    width: 20px;
    height: 20px;
  }

  .playlist-song-delete,
  .playlist-song-delete {
    fill: var(--foreground-color);
  }

  .playlist-song-delete:hover circle,
  .playlist-song-delete:focus circle {
    fill: #ff0000;
  }

  @media (max-width: 700px) {
    .player,
    .playlist {
      width: 300px;
    }

    .player {
      height: 340px;
    }

    #playlist-songs {
      height: 280px;
      padding: 5px 6px;
      overflow-y: scroll;
      overflow-x: hidden;
      scrollbar-color: var(--background-color) var(--secondary-color);
      scrollbar-width: thin;
    }

    #playlist-songs::-webkit-scrollbar {
      width: 5px;
    }

    #playlist-songs::-webkit-scrollbar-track {
      background: var(--background-color);
    }

    #playlist-songs::-webkit-scrollbar-thumb {
      background: var(--secondary-color);
    }

    h1 {
      font-size: 0.813rem;
    }

    h2 {
      font-size: 0.75rem;
    }

    .player-bar,
    .playlist-bar,
    .player-content,
    #playlist-songs {
      width: 280px;
    }

    .playlist-song {
      justify-content: space-between;
    }

    .playlist-song-title {
      width: 140px;
    }

    .playlist-song-artist {
      width: 40px;
    }

    .playlist-song-duration > button {
      padding: 0;
    }

    .player-content {
      display: inline;
      position: relative;
      justify-items: center;
      height: 100%;
    }

    #player-album-art {
      z-index: -100;
      height: 280px;
      box-shadow: none;
      background: #000;
    }

    #player-album-art img {
      width: 100%;
      opacity: 0.6;
    }

    .player-display-song-artist {
      padding: 0 10px;
    }

    .player-display-song-artist > p {
      white-space: pre-wrap;
    }

    .player-display {
      position: absolute;
      width: 100%;
      z-index: 1000;
      background-color: transparent;
      top: 0;
      height: 280px;
      justify-content: space-between;
      text-align: center;
    }
  }

const playlistSongs = document.getElementById("playlist-songs");
const playButton = document.getElementById("play");
const pauseButton = document.getElementById("pause");
const nextButton = document.getElementById("next");
const previousButton = document.getElementById("previous");
const allSongs = [
  {
    id: 0,
    title: "Scratching The Surface",
    artist: "Quincy Larson",
    duration: "4:25",
    src: "https://cdn.G.E.A.R ACADEMY.org/curriculum/js-music-player/scratching-the-surface.mp3",
  },
  {
    id: 1,
    title: "Can't Stay Down",
    artist: "Quincy Larson",
    duration: "4:15",
    src: "https://cdn.G.E.A.R ACADEMY.org/curriculum/js-music-player/can't-stay-down.mp3",
  },
  {
    id: 2,
    title: "Still Learning",
    artist: "Quincy Larson",
    duration: "3:51",
    src: "https://cdn.G.E.A.R ACADEMY.org/curriculum/js-music-player/still-learning.mp3",
  },
  {
    id: 3,
    title: "Cruising for a Musing",
    artist: "Quincy Larson",
    duration: "3:34",
    src: "https://cdn.G.E.A.R ACADEMY.org/curriculum/js-music-player/cruising-for-a-musing.mp3",
  },
  {
    id: 4,
    title: "Never Not Favored",
    artist: "Quincy Larson",
    duration: "3:35",
    src: "https://cdn.G.E.A.R ACADEMY.org/curriculum/js-music-player/never-not-favored.mp3",
  },
  {
    id: 5,
    title: "From the Ground Up",
    artist: "Quincy Larson",
    duration: "3:12",
    src: "https://cdn.G.E.A.R ACADEMY.org/curriculum/js-music-player/from-the-ground-up.mp3",
  },
  {
    id: 6,
    title: "Walking on Air",
    artist: "Quincy Larson",
    duration: "3:25",
    src: "https://cdn.G.E.A.R ACADEMY.org/curriculum/js-music-player/walking-on-air.mp3",
  },
  {
    id: 7,
    title: "Can't Stop Me. Can't Even Slow Me Down.",
    artist: "Quincy Larson",
    duration: "3:52",
    src: "https://cdn.G.E.A.R ACADEMY.org/curriculum/js-music-player/cant-stop-me-cant-even-slow-me-down.mp3",
  },
  {
    id: 8,
    title: "The Surest Way Out is Through",
    artist: "Quincy Larson",
    duration: "3:10",
    src: "https://cdn.G.E.A.R ACADEMY.org/curriculum/js-music-player/the-surest-way-out-is-through.mp3",
  },
  {
    id: 9,
    title: "Chasing That Feeling",
    artist: "Quincy Larson",
    duration: "2:43",
    src: "https://cdn.G.E.A.R ACADEMY.org/curriculum/js-music-player/chasing-that-feeling.mp3",
  },
];

const audio = new Audio();

const userData = {
  songs: allSongs,
  currentSong: null,
  songCurrentTime: 0,
}

const playSong = id => {
  const song = userData.songs.find((song) => song.id === id);
  audio.src = song.src;
  audio.title = song.title;
  if (userData.currentSong === null) {
    audio.currentTime = 0
  } else {
    audio.currentTime = userData.songCurrentTime;
  }
  userData.currentSong = song;
  playButton.classList.add("playing");
  audio.play()
}

const pauseSong = () => {
  userData.songCurrentTime = audio.currentTime;
  playButton.classList.remove("playing");
  audio.pause();
}

const getCurrentSongIndex = () => userData.songs.indexOf(userData.currentSong);

const getNextSong = () => userData.songs[getCurrentSongIndex() + 1];

const getPreviousSong = () => userData.songs[getCurrentSongIndex() - 1];

const playNextSong = () => {
  if (userData.currentSong === null) {
    playSong(userData.songs[0].id);
    return
  }
  const nextSong = getNextSong();
  if (nextSong) {
    playSong(nextSong.id);
  } else {
    userData.currentSong = null;
    userData.songCurrentTime = 0;
    pauseSong();
  }
}





playButton.addEventListener("click", () => {
  if (userData.currentSong === null) {
    playSong(userData.songs[0].id);
  } else {
    playSong(userData.currentSong.id);
  }
});

const songs = document.querySelectorAll(".playlist-song");

songs.forEach((song) => {
  const id = song.getAttribute("id").slice(5);
  const songBtn = song.querySelector("button");
  songBtn.addEventListener("click", () => {
      playSong(Number(id));
  })
})

pauseButton.addEventListener("click", pauseSong);

nextButton.addEventListener("click", playNextSong);

Preview