Function getURLModifier

src/inject/dynamic-theme/modify-css.ts:484–577

(urlValue: string)

        };

        const getURLModifier = (urlValue: string) => {
            if (!didTryLoadCache) {
                didTryLoadCache = true;
                readImageDetailsCache(imageDetailsCache);
            }

            let url = getCSSURLValue(urlValue);
            const isURLEmpty = url.length === 0;
            const {parentStyleSheet} = rule;
            const ownerNode = parentStyleSheet?.ownerNode;
            const scope = (parentStyleSheet && getSheetScope(parentStyleSheet)) ?? document;
            const baseURL = (parentStyleSheet && parentStyleSheet.href) ?
                getCSSBaseBath(parentStyleSheet.href) :
                ownerNode?.baseURI || location.origin;
            url = getAbsoluteURL(baseURL, url);

            return async (theme: Theme): Promise<string | null> => {
                if (isURLEmpty) {
                    return "url('')";
                }

                let selector = rule.selectorText;
                if (selector) {
                    if (selector.includes('::before')) {
                        selector = selector.replaceAll('::before', '');
                    }
                    if (selector.includes('::after')) {
                        selector = selector.replaceAll('::after', '');
                    }
                    if (!scope.querySelector(selector)) {
                        await new Promise<void>((resolve) => {
                            if (imageSelectorQueue.has(selector)) {
                                imageSelectorQueue.get(selector)!.push(resolve);
                            } else {
                                imageSelectorQueue.set(selector, [resolve]);
                                imageSelectorValues.set(selector, urlValue);
                            }
                        });
                    }
                }

                let imageDetails: ImageDetails | null = null;
                if (imageDetailsCache.has(url)) {
                    imageDetails = imageDetailsCache.get(url)!;
                } else {
                    try {
                        if (!isBlobURLCheckResultReady()) {
                            await requestBlobURLCheck();
                        }
                        if (awaitingForImageLoading.has(url)) {
                            const awaiters = awaitingForImageLoading.get(url)!;
                            imageDetails = await new Promise<ImageDetails | null>((resolve) => awaiters.push(resolve));
                            if (!imageDetails) {
                                return null;
                            }
                        } else {
                            awaitingForImageLoading.set(url, []);
                            imageDetails = await getImageDetails(url);