return-youtube-dislike/Extensions/chrome/script.js

(function(securityToken, extensionId) {
    function getButtons() {
        return document
            .getElementById("menu-container")
            ?.querySelector("#top-level-buttons-computed");
    }

    function getLikeButton() {
        return getButtons().children[0];
    }

    function getDislikeButton() {
        return getButtons().children[1];
    }

    function isVideoLiked() {
        return getLikeButton().classList.contains("style-default-active");
    }

    function isVideoDisliked() {
        return getDislikeButton().classList.contains("style-default-active");
    }

    function isVideoNotLiked() {
        return getLikeButton().classList.contains("style-text");
    }

    function isVideoNotDisliked() {
        return getDislikeButton().classList.contains("style-text");
    }

    function getState() {
        if (isVideoLiked()) {
            return "liked";
        }
        if (isVideoDisliked()) {
            return "disliked";
        }
        return "neutral";
    }

    function setLikes(likesCount) {
        getButtons().children[0].querySelector("#text").innerText = likesCount;
    }

    function setDislikes(dislikesCount) {
        getButtons().children[1].querySelector("#text").innerText = dislikesCount;
    }

    function setState() {
        chrome.runtime.sendMessage(extensionId, {
				securityToken: securityToken,
                message: "set_state",
                videoId: getVideoId(),
                state: getState(),
            },
            function(response) {
                if (response != undefined) {
                    const formattedDislike = numberFormat(response.dislikes);
                    // setLikes(response.likes);
                    console.log(response);
                    setDislikes(formattedDislike);
                } else {}
            }
        );
    }

    function likeClicked() {
        console.log("like" + getState());
        setState();
    }

    function dislikeClicked() {
        console.log("dislike" + getState());
        setState();
    }

    function setInitalState() {
        setState();
    }

    function getVideoId() {
        const urlParams = new URLSearchParams(window.location.search);
        const videoId = urlParams.get("v");
        return videoId;
    }

    function isVideoLoaded() {
        const videoId = getVideoId();
        return (
            document.querySelector(`ytd-watch-flexy[video-id='${videoId}']`) !== null
        );
    }

    function numberFormat(numberState) {
        const userLocales = navigator.language;
        const formatter = Intl.NumberFormat(userLocales, { notation: "compact" });
        return formatter.format(numberState);
    }

    function setEventListeners(evt) {
        function checkForJS_Finish() {
            if (getButtons()?.offsetParent && isVideoLoaded()) {
                clearInterval(jsInitChecktimer);
                const buttons = getButtons();
                if (!window.returnDislikeButtonlistenersSet) {
                    buttons.children[0].addEventListener("click", likeClicked);
                    buttons.children[1].addEventListener("click", dislikeClicked);
                    window.returnDislikeButtonlistenersSet = true;
                }
                setInitalState();
            }
        }

        if (window.location.href.indexOf("watch?") >= 0) {
            var jsInitChecktimer = setInterval(checkForJS_Finish, 111);
        }
    }

    setEventListeners();

})(document.currentScript.getAttribute("security-token"), document.currentScript.getAttribute("extension-id"));