in tutorials/viewer/src/tutorial_view.tsx [78:86]
public getCaptionAtTimestamp(timestamp: number): number {
for (let index = 0; index < this.props.tutorial.captions.length; index++) {
let caption = this.props.tutorial.captions[index];
if (timestamp >= caption.timeBegin && timestamp < caption.timeEnd) {
return index;
}
}
return null;
}