Completed untested versions of playlist and playlist song classes.

Restructured for improved development and deployment pipeline.

Added webpack and configurations for development and production.

Began adding JSDocs.

Added eslint.

src/player/PlaylistSong.js

@@ -1,26 +1,165 @@
-export default function PlaylistSong(url, name, author, playlist) {
-    this._displayName = name;
-    this._author = author;
-    this._url = url;
-    this._mediaStream = null;
-    this._playlist = playlist;
+import SongPlaylist from "./SongPlaylist";
 
-    this.getAudio = function () {
-        if (this.mediaStream) {
-            return this.mediaStream;
+/**
+ * A song with metadata that can be used as part of a {@link SongPlaylist}.
+ */
+export default class PlayListSong {
+
+    /**
+     * Constructs a song for a {@link SongPlaylist}.
+     * 
+     * @param {string} url the url to fetch the song from.
+     * @param {string} name the name of the song.
+     * @param {string} author the author of the song.
+     * @param {SongPlaylist} playlist the {@link SongPlaylist} this song is part of.
+     */
+    constructor(url, name, author, playlist) {
+        this._displayName = name;
+        this._author = author;
+        this._url = url;
+        this._audio = null;
+        this._playlist = playlist;
+
+        /**
+         * Whether or not this song is ready to be played.
+         */
+        this.ready = false;
+    }
+
+    /**
+     * @callback AudioEventCallback
+     * @param {HTMLAudioElement} audio
+     */
+
+    /**
+     * 
+     * @param {AudioEventCallback} [onReady] called when the song is ready, including right away if the song is already ready.
+     * @returns {HTMLAudioElement} The audio element that represents this song.
+     */
+    getAudio(onReady) {
+        if (this._audio) {
+            if (this.ready) {
+                if (onReady) onReady(this._audio);
+                return this._audio;
+            }
+            return this._audio;
         }
-        this.mediaStream = new Audio(url);
-    };
-    this.getDisplayName = function () {
+        this._audio = new Audio(this._url);
+
+        this._audio.addEventListener("canplaythrough", () => {
+            this.ready = true;
+            if (onReady) {
+                onReady(this._audio);
+            }
+        });
+        return this._audio;
+    }
+
+    /**
+     * 
+     * @returns {string} representing the name of the song to be displayed.
+     */
+    getDisplayName = function () {
         return this._displayName;
     };
-    this.getAuthor = function () {
+
+    /**
+     * 
+     * @returns {string} representing the author of the song.
+     */
+    getAuthor = function () {
         return this._getAuthor;
     };
-    this.getUrl = function () {
+
+    /**
+     * 
+     * @returns {string} representing the url at which the file for this song can be found.
+     */
+    getUrl = function () {
         return this._url;
     };
-    this.getPlaylist = function () {
+
+    /**
+     * 
+     * @returns {SongPlaylist} the playlist this song is part of.
+     */
+    getPlaylist = function () {
         return this._playlist;
     };
+
+    /**
+     * 
+     * @returns {boolean} true if and only if there is audio data that is either already loaded or is being loaded.
+     */
+    audioInstantiated() {
+        return this._audio ? true : false;
+    }
+
+    /**
+     * Begins audio playback as soon as possible.
+     */
+    play() {
+        this.getAudio((audio) => {
+            audio.play();
+        });
+    }
+
+    /**
+     * Pauses the audio playback, unless the audio data has yet to be instantiated.
+     */
+    pause() {
+        if (!this.audioInstantiated()) return;
+        this.getAudio((audio) => {
+            audio.pause();
+        });
+    }
+
+    /**
+     * 
+     * @returns {number} the volume on a scale of 0 to 1.
+     */
+    getVolume() {
+        return this.getAudio().volume;
+    }
+
+    /**
+     * 
+     * @param {number} volume a normalized volume on a scale of 0 to 1.
+     */
+    setVolume(volume) {
+        this.getAudio().volume = volume;
+    }
+    /**
+     * 
+     * @returns {number} the number of seconds into the song.
+     */
+    getCurrentTime() {
+        return this.getAudio().currentTime;
+    }
+
+    /**
+     * 
+     * @param {number} currentTime the time position in the song to jump to in seconds.
+     */
+    setCurrentTime(currentTime) {
+        this.getAudio().currentTime = currentTime;
+    }
+
+    /**
+     * 
+     * @returns {number} the duration of the song.
+     */
+    getDuration() {
+        return this.getAudio().duration;
+    }
+
+    /**
+     * Unloads the audio data.
+     */
+    unloadAudio() {
+        if (!this.audioInstantiated()) return;
+        this._audio.pause();
+        this._audio = null;
+        this.ready = false;
+    }
 }