Go top

Add a button help to go top of the page
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Wrap lines
// ==UserScript==
// @name         Go top
// @namespace    https://github.com/K1ethoang
// @version      0.3
// @author       K1ethoang
// @match        *://*/*
// @icon         none
// @grant        none
// @description  Add a button help to go top of the page
// @license      MIT
// ==/UserScript==

(function() {
    'use strict';

    let html = document.querySelector("html");
    let btn = document.createElement("button");

    html.style.scrollBehavior="smooth";

    btn.innerHTML = "Top";
    btn.style.display="none";
    btn.style.position="fixed";
    btn.style.bottom= "20px";
    btn.style.right= "30px";
    btn.style.zIndex="999999";
    btn.style.border= "none";
    btn.style.outline= "none";
    btn.style.backgroundColor= "red";
    btn.style.color= "white";
    btn.style.cursor="pointer";
    btn.style.padding= "12px";
    btn.style.borderRadius="10px";
    btn.style.fontSize="16px";

    btn.addEventListener('mouseover', () => {
    btn.style.backgroundColor = '#555';
    });

    btn.addEventListener('mouseout', () => {
    btn.style.backgroundColor = 'red';
    });

    html.appendChild(btn);

    window.onscroll = function() {scrollFunction()};

    function scrollFunction() {
        if (document.body.scrollTop > 20 || document.documentElement.scrollTop > 20) {
            btn.style.display = "block";
        } else {
            btn.style.display = "none";
        }
    }

    function topFunction() {
        document.body.scrollTop = 0;
        document.documentElement.scrollTop = 0;
    }

    btn.addEventListener('click', topFunction);
})();