Interacting with other javascript classes’ objects inside my class

I have created my class, and inside it, I have an object of YouTube Iframe API and an object of ion Range Slider.

How do I make those 2 other objects interact with each other? I need iframe’s video progress to seek with the RangeSlider position change?

class VideoPlayer {
  constructor(url, numItems, div) {
    ...
    this.player = this.createPlayer();  // this way it seems that I cant refer to this.player from within RangeSlider class
    this.createRangeSlider();
  }
...
  createRangeSlider() {
    // alert(this.player.getDuration());
    $(".js-range-slider").ionRangeSlider({
      type: "double",
      onChange: function (data) {
        this.player.seekTo(data);  // this.player here is unaccessible
      },
    });
  }
  createPlayer() {
    let obj = new YT.Player(`player-${this.numItems}`, {
      width: "640",
      height: "390",
      videoId: this.url,
      events: {
        onReady: this.onPlayerReady,
      },
    });
    return obj;
  }
...
}