Add all subscription from the last watched to Watch Later Playlist

subscriptionToWL.js

(function addAll() {
    let neededVideoId = localStorage.getItem('_lastVideoId');
    neededVideoId = neededVideoId || prompt('Enter id of the last video, or keep empty', '');
    const delay = (ms = 100) => new Promise((resolve) => {
        setTimeout(() => {
            resolve(true);
        }, ms)
    });

    const eventMouseEnter = new Event('mouseenter', { 
        view: window,
        bubbles: false, 
        cancelable: false 
    });

    const eventMouseClick = new MouseEvent('click', {
        view: window,
        bubbles: false,
        cancelable: false,
        detail: 1
    });

    let videos = [];

    const checkWatched = async () => {
        await delay(3e3);

        videos = Array.from(document.querySelectorAll('#items > ytd-grid-video-renderer'));

        const found = neededVideoId ? videos.find(item => item.data.videoId === neededVideoId) : videos.find(item => item.data.isWatched);

        if (found) { 
            observer.disconnect();
            stageSecond();
            return;
        }

        if (videos.length > 0) {
            videos[videos.length - 1].scrollIntoView();
        }
    };

    let timer;
    const runWaiter = () => {
        if (timer) {
            clearTimeout(timer);
        }
        timer = setTimeout(checkWatched, 2e3);
    };

    const processing = video => new Promise(resolve => {
        console.log(video.data.videoId, 'processing');
        const mouseenter = async (event) => {
            await delay(1e3);
            console.log(video.data.videoId, 'mouseenter');
            video.removeEventListener('mouseenter', mouseenter, true);

            setTimeout(async () => {
                const button = video.querySelector('ytd-thumbnail-overlay-toggle-button-renderer:nth-child(1) #icon');

                console.log(video.data.videoId, 'button', button);

                if (button && button.parentNode && button.parentNode.data && !button.parentNode.data.isToggled) {
                    const buttonTap = async (event) => {
                        button.parentNode.removeEventListener('click', buttonTap, true);
                        
                        console.log(video.data.videoId, 'click');
                        await delay(1e2);

                        resolve(true);
                    };

                    button.parentNode.addEventListener('click', buttonTap, true);

                    await delay(2e2);

                    const rect = video.getClientRects()[0];

                    const c = button.dispatchEvent(new MouseEvent('click', {
                        view: window,
                        bubbles: false,
                        cancelable: false,
                        detail: 1,
                        clientX: rect.x + rect.width - 20,
                        clientY: rect.y + 20
                    }));

                    await delay(1e2);

                    if (!c) {
                        resolve(false);
                    }
                } else {
                    resolve(false);
                }
            }, 300);
        }

        video.addEventListener('mouseenter', mouseenter, true);

        video.dispatchEvent(eventMouseEnter);
    });

    const stageSecond = async () => {
        if (neededVideoId) {
            const index = videos.findIndex(item => item.data.videoId === neededVideoId);
            videos.splice(index, videos.length);
        }
        
        videos = videos.filter(item => !item.data.isWatched);

        let l = videos.length;
        let rect;

        while(l--) {
            if (window.breakNow) {
                break;
            }

            window.scrollTo(0, videos[l].offsetTop - 200);

            await delay(100);

            console.log(l);
            await processing(videos[l]);
            videos[l].setAttribute('style', `border: 5px solid red;`);
        }
    };

    const itemsContainer = document.querySelector('ytd-section-list-renderer');

    const mutationListener = (mutationList, observer) => {
        const list = mutationList.filter(item => item.target.id === 'items');

        if (list.length > 0) {
            runWaiter();
        }
    };

    const observer = new MutationObserver(mutationListener);

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

    checkWatched();
})();