render() {
const { playList, slug } = this.props;
const index = playList.findIndex(i => i.slug === slug);
const video = playList[index];
const prev = playList[index - 1];
const next = playList[index + 1];
render(
<div>
{/* ... */}
<div>
{prev && <Link to={`/video/${prev.slug}`}>Prev</Link>}
{next && <Link to={`/video/${next.slug}`}>Next</Link>}
</div>
<div/>
);
}