Function fetchWithFallback

Picviewer CE+/dist.user.js:12467–12500

(urls)

                "https://cdn.jsdelivr.net/npm/video.js@8.23.3/dist/video.min.js"
            ];
            const fetchWithFallback = (urls) => {
                return new Promise((resolve, reject) => {
                    let lastError = null;
                    const urlsToTry = [...urls];

                    const tryNext = () => {
                        if (urlsToTry.length === 0) {
                            reject(new Error(`Failed to load resource after trying all sources. Last error: ${lastError}`));
                            return;
                        }

                        const url = urlsToTry.shift();
                        const xhr = new XMLHttpRequest();
                        xhr.open('GET', url);
                        xhr.onload = () => {
                            if (xhr.status === 200) {
                                resolve(xhr.responseText);
                            } else {
                                lastError = `Status ${xhr.status} from ${url}`;
                                console.warn(`Failed to load ${url}, trying next source...`);
                                tryNext();
                            }
                        };
                        xhr.onerror = () => {
                            lastError = `Network error from ${url}`;
                            console.warn(`Failed to load ${url}, trying next source...`);
                            tryNext();
                        };
                        xhr.send();
                    };

                    tryNext();
                });
            };
            const pCSS = fetchWithFallback(cssSources).then(cssContent => {
                const styleElement = document.createElement('style');
                styleElement.textContent = cssContent;