rx-player/src/compat/add_text_track.ts

Canal+ HTML5 Video Player

/**
 * Copyright 2015 CANAL+ Group
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

import type { ICompatTextTrack, IMediaElement } from "./browser_compatibility_types";
import { isIEOrEdge } from "./browser_detection";

/**
 * Add text track to the given media element.
 *
 * Returns an object with the following properties:
 *   - track {TextTrack}: the added text track
 *   - trackElement {HTMLElement|undefined}: the added <track> element.
 *     undefined if no trackElement was added.
 *
 * @param {HTMLMediaElement} mediaElement
 * @returns {Object}
 */
export default function addTextTrack(mediaElement: IMediaElement): {
  track: ICompatTextTrack;
  trackElement: HTMLTrackElement | undefined;
} {
  let track;
  let trackElement;

  const kind = "subtitles";

  if (isIEOrEdge) {
    const tracksLength = mediaElement.textTracks.length;
    track = (
      tracksLength > 0
        ? mediaElement.textTracks[tracksLength - 1]
        : mediaElement.addTextTrack(kind)
    ) as ICompatTextTrack;
    track.mode = track.SHOWING ?? "showing";
  } else {
    trackElement = document.createElement("track");
    mediaElement.appendChild(trackElement);
    track = trackElement.track;
    trackElement.kind = kind;
    track.mode = "showing";
  }
  return { track, trackElement };
}