1 files changed, 193 insertions, 0 deletions
diff --git a/javascript/videojs/src/js/tracks/track-list.js b/javascript/videojs/src/js/tracks/track-list.js
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+++ b/javascript/videojs/src/js/tracks/track-list.js
@@ -0,0 +1,193 @@
+/**
+ * @file track-list.js
+ */
+import EventTarget from '../event-target';
+import {isEvented} from '../mixins/evented';
+
+/** @import Track from './track' */
+
+/**
+ * Common functionaliy between {@link TextTrackList}, {@link AudioTrackList}, and
+ * {@link VideoTrackList}
+ *
+ * @extends EventTarget
+ */
+class TrackList extends EventTarget {
+  /**
+   * Create an instance of this class
+   *
+   * @param { Track[] } tracks
+   *        A list of tracks to initialize the list with.
+   *
+   * @abstract
+   */
+  constructor(tracks = []) {
+    super();
+
+    this.tracks_ = [];
+
+    for (let i = 0; i < tracks.length; i++) {
+      this.addTrack(tracks[i]);
+    }
+  }
+
+  /**
+   * The current number of `Track`s in this TrackList.
+   *
+   * @type {number}
+   */
+  get length() {
+    return this.tracks_.length;
+  }
+
+  /**
+   * Add a {@link Track} to the `TrackList`
+   *
+   * @param {Track} track
+   *        The audio, video, or text track to add to the list.
+   *
+   * @fires TrackList#addtrack
+   */
+  addTrack(track) {
+    const index = this.tracks_.length;
+
+    if (!('' + index in this)) {
+      Object.defineProperty(this, index, {
+        get() {
+          return this.tracks_[index];
+        }
+      });
+    }
+
+    // Do not add duplicate tracks
+    if (this.tracks_.indexOf(track) === -1) {
+      this.tracks_.push(track);
+      /**
+       * Triggered when a track is added to a track list.
+       *
+       * @event TrackList#addtrack
+       * @type {Event}
+       * @property {Track} track
+       *           A reference to track that was added.
+       */
+      this.trigger({
+        track,
+        type: 'addtrack',
+        target: this
+      });
+    }
+
+    /**
+     * Triggered when a track label is changed.
+     *
+     * @event TrackList#labelchange
+     * @type {Event}
+     * @property {Track} track
+     *           A reference to track whose label was changed.
+     */
+    track.labelchange_ = () => {
+      this.trigger({
+        track,
+        type: 'labelchange',
+        target: this
+      });
+    };
+
+    if (isEvented(track)) {
+      track.addEventListener('labelchange', track.labelchange_);
+    }
+  }
+
+  /**
+   * Remove a {@link Track} from the `TrackList`
+   *
+   * @param {Track} rtrack
+   *        The audio, video, or text track to remove from the list.
+   *
+   * @fires TrackList#removetrack
+   */
+  removeTrack(rtrack) {
+    let track;
+
+    for (let i = 0, l = this.length; i < l; i++) {
+      if (this[i] === rtrack) {
+        track = this[i];
+        if (track.off) {
+          track.off();
+        }
+
+        this.tracks_.splice(i, 1);
+
+        break;
+      }
+    }
+
+    if (!track) {
+      return;
+    }
+
+    /**
+     * Triggered when a track is removed from track list.
+     *
+     * @event TrackList#removetrack
+     * @type {Event}
+     * @property {Track} track
+     *           A reference to track that was removed.
+     */
+    this.trigger({
+      track,
+      type: 'removetrack',
+      target: this
+    });
+  }
+
+  /**
+   * Get a Track from the TrackList by a tracks id
+   *
+   * @param {string} id - the id of the track to get
+   * @method getTrackById
+   * @return {Track}
+   * @private
+   */
+  getTrackById(id) {
+    let result = null;
+
+    for (let i = 0, l = this.length; i < l; i++) {
+      const track = this[i];
+
+      if (track.id === id) {
+        result = track;
+        break;
+      }
+    }
+
+    return result;
+  }
+}
+
+/**
+ * Triggered when a different track is selected/enabled.
+ *
+ * @event TrackList#change
+ * @type {Event}
+ */
+
+/**
+ * Events that can be called with on + eventName. See {@link EventHandler}.
+ *
+ * @property {Object} TrackList#allowedEvents_
+ * @protected
+ */
+TrackList.prototype.allowedEvents_ = {
+  change: 'change',
+  addtrack: 'addtrack',
+  removetrack: 'removetrack',
+  labelchange: 'labelchange'
+};
+
+// emulate attribute EventHandler support to allow for feature detection
+for (const event in TrackList.prototype.allowedEvents_) {
+  TrackList.prototype['on' + event] = null;
+}
+
+export default TrackList;