Userscript to solve liveworksheets.com exercises

liveworksheets.user.js

// ==UserScript==
// @name         Liveworksheets.com solver
// @namespace    https://mvolfik.github.io/
// @version      0.2
// @description  Add button to autofill liveworksheets.com
// @author       Matěj Volf
// @match        https://www.liveworksheets.com/*
// @downloadUrl  https://gist.github.com/mvolfik/5d663fd304c38a872813e0576a58573a/raw/liveworksheets.user.js
// @updateUrl    https://gist.github.com/mvolfik/5d663fd304c38a872813e0576a58573a/raw/liveworksheets.user.js
// @grant        none
// ==/UserScript==

(function() {
    'use strict';

    const but = document.createElement("button");
    but.style.position = "absolute";
    but.style.top = "0";
    but.style.left = "0";
    but.style["z-index"] = "999";
    but.innerText = "Fill correct values";

    function fillItem(i, value) {
        const is = i.toString();
        const textbox = document.getElementById("textbox" + is);
        if (textbox !== null) {
            textbox.innerText = value;
            return true
        }

        const select = document.getElementById("selectablediv" + is);
        if (select !== null) {
            if (select.classList.contains("selectedselectablediv") !== (value === "select:yes")) {
                console.log(`selectanswer({is})`);
                window.selectanswer(i);
            }
            return true
        }
    }
    function clickHandler() {
        but.remove();

        const data = JSON.parse(window.contenidojson);
        const failed = [];
        data.forEach(function(values, i){
            const is = i.toString();
            try {
                if (fillItem(i, values[0])) {
                    return
                }
            } catch (e) {}
            failed.push(is);
        });
        const sub = document.getElementById("capafinish");
        sub.scrollIntoView({block: "center"});
        if (failed.length > 0) {
            alert("Failed to autofill these items: " + failed.join(", "));
        }

    }
    but.addEventListener("click", clickHandler);
    document.getElementById("capa1").insertAdjacentElement("afterbegin", but);
})();

what do i do to make it work

@grcie this is a userscript, which you can install using a userscript manager (a browser extension), for example Tampermonkey. If that's not your question, I cannot provide any support beyond that - I made this a while ago and don't use it anymore. It worked for me at the time, so I just pasted it online, but that's it.

This is open source software, hereby declared to be under the MIT license. Please note the THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND [...] part.