youtube dislikes

// ==UserScript==
// @name         Display dislike count
// @namespace    http://tampermonkey.net/
// @version      0.1
// @author       Anonymous
// @match        https://www.youtube.com/*
// @icon         https://www.google.com/s2/favicons?domain=youtube.com
// @grant        none
// ==/UserScript==

function format(number) {
    if (number < 1000)
        return number;
    if (number < 10000)
        return Math.floor(number/100)/10 + "k";
    return Math.floor(number/1000) + "k";
}

async function updateDislikes() {
    if (location.href.search(/v=[0-9a-zA-Z_-]{11}/)){
        let element = document.querySelector('#button[aria-label="Dislike this video"]');
        if (element) {
            element.parentElement.parentElement.querySelector("#text").textContent = "...";
        }
        let response = await fetch(location.href);
        let text = await response.text();
        let ratio = (text.match(/averageRating":([\d\.]*)/)[1] - 1) / 4;
        let likeCount = text.match(/label":"([\d,]*) likes/)[1];
        likeCount = likeCount.replace(/\D/g, '');
        let dislikeCount = likeCount / ratio - likeCount;
        document.querySelector('#button[aria-label="Dislike this video"]').parentElement.parentElement.querySelector("#text").textContent = format(Math.round(dislikeCount));
    }
}

document.addEventListener("yt-navigate-finish", updateDislikes);
window.addEventListener("load", updateDislikes);
setInterval(updateDislikes, 3 * 60 * 1000);