$ npm install thumbnail-youtube-vimeo
var thumbnailYoutubeVimeo = require('thumbnail-youtube-vimeo');
thumbnailYoutubeVimeo('https://www.youtube.com/watch?v=dQw4w9WgXcQ')
.then(
result => {console.log(result)/* //img.youtube.com/vi/dQw4w9WgXcQ/0.jpg */},
err => {console.error(err)}
);