src/source-updater.js
/**
   * Whether the underlying sourceBuffer is updating or not
   *
   * @return {Boolean} the updating status of the SourceBuffer
   */
Whether the underlying sourceBuffer is updating or not
@return {Boolean} the updating status of the SourceBuffer
Whether the underlying sourceBuffer is updating or not @return { Boolean } the updating status of the SourceBuffer
updating() {
    return !this.sourceBuffer_ || this.sourceBuffer_.updating ||
      (!!this.pendingCallback_ && this.pendingCallback_ !== noop);
  }
updating ( ) { return ! this . sourceBuffer_ || this . sourceBuffer_ . updating || ( ! ! this . pendingCallback_ && this . pendingCallback_ !== noop ) ; }
Whether the underlying sourceBuffer is updating or not
 @return {Boolean} the updating status of the SourceBuffer
Whether the underlying sourceBuffer is updating or not @return { Boolean } the updating status of the SourceBuffer
// we are updating if the sourcebuffer is updating or // if we have a pending callback that is not our internal noop