lib.js

// base64 favicon
// https://abs.twimg.com/favicons/twitter.2.ico
const TWITTER_FAVICON = "data:image/x-icon;base64,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";

/**
 * 単数用
 * @param {string} selector 
 */
function waitForSelector(selector) {
    return new Promise((resolve) => {
        if (document.querySelector(selector)) return resolve(document.querySelector(selector));

        const observer = new MutationObserver(() => {
            if (document.querySelector(selector)) {
                resolve(document.querySelector(selector));
                observer.disconnect();
            }
        });

        observer.observe(document, {
            childList: true,
            subtree: true
        });
    });
}

/**
 * 複数用
 * @param {string} selector 
 */
function waitForSelectors(selector) {
    return new Promise((resolve) => {
        const elements = document.querySelectorAll(selector);

        if (elements.length > 0) {
            resolve(elements);
        } else {
            const observer = new MutationObserver(() => {
                const updatedElements = document.querySelectorAll(selector);
                if (updatedElements.length > 0) {
                    resolve(updatedElements);
                    observer.disconnect();
                }
            });

            observer.observe(document, {
                childList: true,
                subtree: true
            });
        }
    });
}