Load youtube videos async

video_loader.js

let videos = $(".wpl-youtube");

$.each(videos, function () {
    let self = $(this);
    let thumbnail = self.find('img');
    let play = self.find('.wpl-play');
    // Based on the YouTube ID, we can easily find the thumbnail image
    thumbnail.attr('src', 'https://i.ytimg.com/vi/' + self.attr('data-id') + '/0.jpg');

    play.on({
        click: function () {
            // Create an iFrame with autoplay set to true
            let iframe = $("<iframe />");
            let iframe_url = "https://www.youtube-nocookie.com/embed/" + self.attr('data-id') + "?autoplay=1&autohide=1&rel=0&amp;showinfo=0";
            if (self.attr("data-params")) iframe_url += '&' + self.attr("data-params");
            iframe.attr("src", iframe_url);
            iframe.attr("frameborder", '0');
            iframe.attr("class", 'embed-responsive-item');
            iframe.attr("allow", 'autoplay; encrypted-media');
            iframe.attr("allowfullscreen", true);

            // The height and width of the iFrame should be the same as parent
            self.attr('class', 'embed-responsive embed-responsive-16by9');
            // Replace the YouTube thumbnail with YouTube Player
            self.html(iframe);
        }
    })
});