https://sdbullion.com/static/version1790244112/frontend/SDBullion/…/Magento_Theme/js/lite-yt-embed.min.js

1/**
2 * A lightweight youtube embed. Still should feel the same to the user, just MUCH faster to initialize and paint.
3 *
4 * Thx to these as the inspiration
5 *   https://storage.googleapis.com/amp-vs-non-amp/youtube-lazy.html
6 *   https://autoplay-youtube-player.glitch.me/
7 *
8 * Once built it, I also found these:
9 *   https://github.com/ampproject/amphtml/blob/master/extensions/amp-youtube (👍👍)
10 *   https://github.com/Daugilas/lazyYT
11 *   https://github.com/vb/lazyframe
12 */
13class LiteYTEmbed extends HTMLElement {
14    connectedCallback() {
15        this.videoId = this.getAttribute('videoid');
16
17        let playBtnEl = this.querySelector('.lty-playbtn');
18        // A label for the button takes priority over a [playlabel] attribute on the custom-element
19        this.playLabel = (playBtnEl && playBtnEl.textContent.trim()) || this.getAttribute('playlabel') || 'Play';
20
21        this.dataset.title = this.getAttribute('title') || "";
22
23        /**
24         * Lo, the youtube poster image!  (aka the thumbnail, image placeholder, etc)
25         *
26         * See https://github.com/paulirish/lite-youtube-embed/blob/master/youtube-thumbnail-urls.md
27         */
28        if (!this.style.backgroundImage) {
29          this.style.backgroundImage = `url("https://i.ytimg.com/vi/${this.videoId}/hqdefault.jpg")`;
30          this.upgradePosterImage();
31        }
32
33        // Set up play button, and its visually hidden label
34        if (!playBtnEl) {
35            playBtnEl = document.createElement('button');
36            playBtnEl.type = 'button';
37            playBtnEl.classList.add('lty-playbtn');
38            this.append(playBtnEl);
39        }
40        if (!playBtnEl.textContent) {
41            const playBtnLabelEl = document.createElement('span');
42            playBtnLabelEl.className = 'lyt-visually-hidden';
43            playBtnLabelEl.textContent = this.playLabel;
44            playBtnEl.append(playBtnLabelEl);
45        }
46
47        this.addNoscriptIframe();
48
49        playBtnEl.removeAttribute('href');
50
51        // On hover (or tap), warm up the TCP connections we're (likely) about to use.
52        this.addEventListener('pointerover', LiteYTEmbed.warmConnections, {once: true});
53
54        // Once the user clicks, add the real iframe and drop our play button
55        // TODO: In the future we could be like amp-youtube and silently swap in the iframe during idle time
56        //   We'd want to only do this for in-viewport or near-viewport ones: https://github.com/ampproject/amphtml/pull/5003
57        this.addEventListener('click', this.activate);
58
59        // Chrome & Edge desktop have no problem with the basic YouTube Embed with ?autoplay=1
60        // However Safari desktop and most/all mobile browsers do not successfully track the user gesture of clicking through the creation/loading of the iframe,
61        // so they don't autoplay automatically. Instead we must load an additional 2 sequential JS files (1KB + 165KB) (un-br) for the YT Player API
62        // TODO: Try loading the the YT API in parallel with our iframe and then attaching/playing it. #82
63        this.needsYTApi = this.hasAttribute("js-api") || navigator.vendor.includes('Apple') || navigator.userAgent.includes('Mobi');
64    }
65
66    /**
67     * Add a <link rel={preload | preconnect} ...> to the head
68     */
69    static addPrefetch(kind, url, as) {
70        const linkEl = document.createElement('link');
71        linkEl.rel = kind;
72        linkEl.href = url;
73        if (as) {
74            linkEl.as = as;
75        }
76        document.head.append(linkEl);
77    }
78
79    /**
80     * Begin pre-connecting to warm up the iframe load
81     * Since the embed's network requests load within its iframe,
82     *   preload/prefetch'ing them outside the iframe will only cause double-downloads.
83     * So, the best we can do is warm up a few connections to origins that are in the critical path.
84     *
85     * Maybe `<link rel=preload as=document>` would work, but it's unsupported: http://crbug.com/593267
86     * But TBH, I don't think it'll happen soon with Site Isolation and split caches adding serious complexity.
87     */
88    static warmConnections() {
89        if (LiteYTEmbed.preconnected) return;
90
91        // The iframe document and most of its subresources come right off youtube.com
92        LiteYTEmbed.addPrefetch('preconnect', 'https://www.youtube-nocookie.com');
93        // The botguard script is fetched off from google.com
94        LiteYTEmbed.addPrefetch('preconnect', 'https://www.google.com');
95
96        // Not certain if these ad related domains are in the critical path. Could verify with domain-specific throttling.
97        LiteYTEmbed.addPrefetch('preconnect', 'https://googleads.g.doubleclick.net');
98        LiteYTEmbed.addPrefetch('preconnect', 'https://static.doubleclick.net');
99
100        LiteYTEmbed.preconnected = true;
101    }
102
103    fetchYTPlayerApi() {
104        if (window.YT || (window.YT && window.YT.Player)) return;
105
106        this.ytApiPromise = new Promise((res, rej) => {
107            var el = document.createElement('script');
108            el.src = 'https://www.youtube.com/iframe_api';
109            el.async = true;
110            el.onload = _ => {
111                YT.ready(res);
112            };
113            el.onerror = rej;
114            this.append(el);
115        });
116    }
117
118    /** Return the YT Player API instance. (Public L-YT-E API) */
119    async getYTPlayer() {
120        if(!this.playerPromise) {
121            await this.activate();
122        }
123
124        return this.playerPromise;
125    }
126
127    async addYTPlayerIframe() {
128        this.fetchYTPlayerApi();
129        await this.ytApiPromise;
130
131        const videoPlaceholderEl = document.createElement('div')
132        this.append(videoPlaceholderEl);
133
134        const paramsObj = Object.fromEntries(this.getParams().entries());
135
136        this.playerPromise = new Promise(resolve => {
137            let player = new YT.Player(videoPlaceholderEl, {
138                width: '100%',
139                videoId: this.videoId,
140                playerVars: paramsObj,
141                events: {
142                    'onReady': event => {
143                        event.target.playVideo();
144                        resolve(player);
145                    }
146                }
147            });
148        });
149    }
150
151    // Add the iframe within <noscript> for indexability discoverability. See https://github.com/paulirish/lite-youtube-embed/issues/105
152    addNoscriptIframe() {
153        const iframeEl = this.createBasicIframe();
154        const noscriptEl = document.createElement('noscript');
155        // Appending into noscript isn't equivalant for mysterious reasons: https://html.spec.whatwg.org/multipage/scripting.html#the-noscript-element
156        noscriptEl.innerHTML = iframeEl.outerHTML;
157        this.append(noscriptEl);
158    }
159
160    getParams() {
161        const params = new URLSearchParams(this.getAttribute('params') || []);
162        params.append('autoplay', '1');
163        params.append('playsinline', '1');
164        return params;
165    }
166
167    async activate(){
168        if (this.classList.contains('lyt-activated')) return;
169        this.classList.add('lyt-activated');
170
171        if (this.needsYTApi) {
172            return this.addYTPlayerIframe(this.getParams());
173        }
174
175        const iframeEl = this.createBasicIframe();
176        this.append(iframeEl);
177
178        // Set focus for a11y

179        iframeEl.focus();
180    }
181
182    createBasicIframe(){
183        const iframeEl = document.createElement('iframe');
184        iframeEl.width = 560;
185        iframeEl.height = 315;
186        // No encoding necessary as [title] is safe. https://cheatsheetseries.owasp.org/cheatsheets/Cross_Site_Scripting_Prevention_Cheat_Sheet.html#:~:text=Safe%20HTML%20Attributes%20include
187        iframeEl.title = this.playLabel;
188        iframeEl.allow = 'accelerometer; autoplay; encrypted-media; gyroscope; picture-in-picture';
189        iframeEl.allowFullscreen = true;
190        // AFAIK, the encoding here isn't necessary for XSS, but we'll do it only because this is a URL
191        // https://stackoverflow.com/q/64959723/89484
192        iframeEl.src = `https://www.youtube-nocookie.com/embed/${encodeURIComponent(this.videoId)}?${this.getParams().toString()}`;
193        return iframeEl;
194    }
195
196    /**
197     * In the spirit of the `lowsrc` attribute and progressive JPEGs, we'll upgrade the reliable
198     * poster image to a higher resolution one, if it's available.
199     * Interestingly this sddefault webp is often smaller in filesize, but we will still attempt it second
200     * because getting _an_ image in front of the user if our first priority.
201     *
202     * See https://github.com/paulirish/lite-youtube-embed/blob/master/youtube-thumbnail-urls.md for more details
203     */
204    upgradePosterImage() {
205         // Defer to reduce network contention.
206        setTimeout(() => {
207            const webpUrl = `https://i.ytimg.com/vi_webp/${this.videoId}/sddefault.webp`;
208            const img = new Image();
209            img.fetchPriority = 'low'; // low priority to reduce network contention
210            img.referrerpolicy = 'origin'; // Not 100% sure it's needed, but https://github.com/ampproject/amphtml/pull/3940
211            img.src = webpUrl;
212            img.onload = e => {
213                // A pretty ugly hack since onerror won't fire on YouTube image 404. This is (probably) due to
214                // Youtube's style of returning data even with a 404 status. That data is a 120x90 placeholder image.
215                // … per "annoying yt 404 behavior" in the .md
216                const noAvailablePoster = e.target.naturalHeight == 90 && e.target.naturalWidth == 120;
217                if (noAvailablePoster) return;
218
219                this.style.backgroundImage = `url("${webpUrl}")`;
220            }
221        }, 100);
222    }
223}
224// Register custom element
225customElements.define('lite-youtube', LiteYTEmbed);