Back to Top

为网页添加平滑返回顶部按钮

Tendrás que instalar una extensión para tu navegador como Tampermonkey, Greasemonkey o Violentmonkey si quieres utilizar este script.

You will need to install an extension such as Tampermonkey to install this script.

Necesitarás instalar una extensión como Tampermonkey o Violentmonkey para instalar este script.

Necesitarás instalar una extensión como Tampermonkey o Userscripts para instalar este script.

Necesitará instalar una extensión como Tampermonkey para instalar este script.

Necesitarás instalar una extensión para administrar scripts de usuario si quieres instalar este script.

(Ya tengo un administrador de scripts de usuario, déjame instalarlo)

Necesitará instalar una extensión como Stylus para instalar este estilo.

Necesitará instalar una extensión como Stylus para instalar este estilo.

Necesitará instalar una extensión como Stylus para instalar este estilo.

Necesitará instalar una extensión del gestor de estilos de usuario para instalar este estilo.

Necesitará instalar una extensión del gestor de estilos de usuario para instalar este estilo.

Necesitará instalar una extensión del gestor de estilos de usuario para instalar este estilo.

(Ya tengo un administrador de estilos de usuario, déjame instalarlo)

// ==UserScript==
// @name         Back to Top
// @namespace    http://tampermonkey.net/
// @version      0.10
// @description  为网页添加平滑返回顶部按钮
// @author       sept
// @match        *://*/*
// @grant        GM_getValue
// @grant        GM_setValue
// @grant        GM_registerMenuCommand
// @license      MIT
// @icon         data:image/png;base64,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
// ==/UserScript==

(function () {
    'use strict';

    if (window.self !== window.top || window.myBackToTopScriptHasRun) {
        return;
    }
    window.myBackToTopScriptHasRun = true;

    const HOSTNAME = window.location.hostname;
    const ENABLED_SITES_KEY = 'back-to-top-enabled-sites';
    const BUTTON_POSITION_KEY = `back-to-top-button-position_${HOSTNAME}`;

    // 获取已启用的网站列表,默认为 a list of 'github.com'
    let enabledSites = GM_getValue(ENABLED_SITES_KEY, ['github.com']);

    // 检查当前网站是否已启用
    function isSiteEnabled() {
        return enabledSites.includes(HOSTNAME);
    }

    // 切换当前网站的启用状态
    function toggleSite() {
        if (isSiteEnabled()) {
            enabledSites = enabledSites.filter(site => site !== HOSTNAME);
        } else {
            enabledSites.push(HOSTNAME);
        }
        GM_setValue(ENABLED_SITES_KEY, enabledSites);
        window.location.reload();
    }

    // 注册菜单命令
    GM_registerMenuCommand(`${isSiteEnabled() ? '关闭' : '开启'}返回顶部`, toggleSite);

    // 如果当前网站未启用,则不执行任何操作
    if (!isSiteEnabled()) {
        return;
    }

    // 创建按钮元素
    const backToTopBtn = document.createElement('div');
    backToTopBtn.id = 'gemini-back-to-top-button';
    backToTopBtn.innerHTML = '↑';

    // 创建样式
    const style = document.createElement('style');
    style.textContent = `
        #gemini-back-to-top-button {
            position: fixed;
            width: 40px;
            height: 40px;
            border-radius: 50%;
            background: linear-gradient(135deg, #238636, #2ea043);
            color: white;
            display: flex;
            justify-content: center;
            align-items: center;
            cursor: pointer;
            box-shadow: 0 4px 12px rgba(0,0,0,0.2);
            opacity: 0;
            transition: opacity 0.3s, transform 0.3s;
            font-size: 20px;
            font-weight: bold;
            z-index: 9999;
        }

        #gemini-back-to-top-button.visible {
            opacity: 1;
        }

        #gemini-back-to-top-button:hover {
            transform: scale(1.1);
            box-shadow: 0 6px 16px rgba(0,0,0,0.2);
        }

        #gemini-back-to-top-button:active {
            cursor: pointer;
            transform: scale(0.9);
        }
    `;

    // 添加样式和按钮到页面
    document.head.appendChild(style);
    document.body.appendChild(backToTopBtn);

    function applyPosition(position) {
        let top, left;

        const buttonWidth = 40;
        const buttonHeight = 40;

        if (position.pctTop !== undefined && position.pctLeft !== undefined) {
            top = position.pctTop * (window.innerHeight - buttonHeight);
            left = position.pctLeft * (window.innerWidth - buttonWidth);
        } else if (position.top !== undefined && position.left !== undefined) {
            top = position.top;
            left = position.left;
        } else {
            return;
        }

        top = Math.max(0, Math.min(top, window.innerHeight - buttonHeight));
        left = Math.max(0, Math.min(left, window.innerWidth - buttonWidth));

        backToTopBtn.style.top = `${top}px`;
        backToTopBtn.style.left = `${left}px`;
    }

    const defaultPosition = { pctTop: 0.9, pctLeft: 0.9 };
    const savedPosition = GM_getValue(BUTTON_POSITION_KEY, defaultPosition);
    applyPosition(savedPosition);

    function smoothScrollTo(targetY, duration) {
        const startY = window.pageYOffset;
        const distance = targetY - startY;
        let startTime = null;

        function animation(currentTime) {
            if (startTime === null) startTime = currentTime;
            const timeElapsed = currentTime - startTime;
            const run = ease(timeElapsed, startY, distance, duration);
            window.scrollTo(0, run);
            if (timeElapsed < duration) requestAnimationFrame(animation);
        }

        // easeInOutQuad easing function
        function ease(t, b, c, d) {
            t /= d / 2;
            if (t < 1) return c / 2 * t * t + b;
            t--;
            return -c / 2 * (t * (t - 2) - 1) + b;
        }

        requestAnimationFrame(animation);
    }


    // 滚动事件监听
    window.addEventListener('scroll', function () {
        if (window.pageYOffset > 300) {
            backToTopBtn.classList.add('visible');
        } else {
            backToTopBtn.classList.remove('visible');
        }
    });

    // 窗口大小调整事件监听
    window.addEventListener('resize', () => {
        const pos = GM_getValue(BUTTON_POSITION_KEY, defaultPosition);
        applyPosition(pos);
    });

    let isDragging = false;
    let hasDragged = false;
    let offsetX, offsetY, startX, startY;

    backToTopBtn.addEventListener('mousedown', (e) => {
        isDragging = true;
        hasDragged = false;
        startX = e.clientX;
        startY = e.clientY;
        offsetX = e.clientX - backToTopBtn.getBoundingClientRect().left;
        offsetY = e.clientY - backToTopBtn.getBoundingClientRect().top;
        backToTopBtn.style.transition = 'none'; // Disable transition during drag
    });

    document.addEventListener('mousemove', (e) => {
        if (isDragging) {
            const dx = e.clientX - startX;
            const dy = e.clientY - startY;
            if (Math.sqrt(dx * dx + dy * dy) > 5) {
                hasDragged = true;
            }

            if (hasDragged) {
                let newTop = e.clientY - offsetY;
                let newLeft = e.clientX - offsetX;

                // Constrain to viewport
                newTop = Math.max(0, Math.min(newTop, window.innerHeight - backToTopBtn.offsetHeight));
                newLeft = Math.max(0, Math.min(newLeft, window.innerWidth - backToTopBtn.offsetWidth));

                backToTopBtn.style.top = `${newTop}px`;
                backToTopBtn.style.left = `${newLeft}px`;
            }
        }
    });

    document.addEventListener('mouseup', () => {
        if (isDragging) {
            isDragging = false;
            backToTopBtn.style.transition = 'opacity 0.3s, transform 0.3s'; // Re-enable transition
            if (hasDragged) {
                const pctTop = backToTopBtn.offsetTop / (window.innerHeight - backToTopBtn.offsetHeight);
                const pctLeft = backToTopBtn.offsetLeft / (window.innerWidth - backToTopBtn.offsetWidth);

                GM_setValue(BUTTON_POSITION_KEY, {
                    pctTop: Math.max(0, Math.min(1, pctTop)),
                    pctLeft: Math.max(0, Math.min(1, pctLeft)),
                });
            }
        }
    });

    // 点击事件 - 平滑滚动
    backToTopBtn.addEventListener('click', function () {
        if (!hasDragged) {
            smoothScrollTo(0, 300);
        }
    });
})();