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置頂和置底按鈕

在所有頁面生成兩個按鈕，一個用於順滑回到頂部，一個用於持續滾動到底部，再次點擊取消滾動到底部

// ==UserScript==
// @name        置頂和置底按鈕
// @version     1.4
// @description 在所有頁面生成兩個按鈕，一個用於順滑回到頂部，一個用於持續滾動到底部，再次點擊取消滾動到底部
// @run-at      document-end
// @match       *://*/*
// @license     MIT
// @namespace   https://greasyfork.org/zh-CN/users/954189
// ==/UserScript==

(function() {
    'use strict';

    var style = document.createElement('style');
    style.innerHTML = `
    .GO_TO_TOP_button, .GO_TO_BOTTOM_button {
        width: 29.4px;  /* 縮小30% */
        height: 29.4px;  /* 縮小30% */
        border-radius: 5.6px;  /* 縮小30% */
        box-shadow: 0 3px 6px rgb(0 0 0 / 16%), 0 1px 2px rgb(0 0 0 / 23%);
        position: fixed;
        right: 14px;  /* 縮小30% */
        display: flex;
        align-items: center;
        justify-content: center;
        z-index: 99999999;
        background-color: white;
        opacity: 0.8;
        transition: opacity 0.2s ease-in-out;
        cursor: pointer;
    }
    .GO_TO_TOP_button svg, .GO_TO_BOTTOM_button svg {
        width: 16.8px;  /* 縮小30% */
        height: 16.8px;  /* 縮小30% */
        margin: 0;
    }
    .GO_TO_TOP_button {
        bottom: 49px;  /* 縮小30% */
    }
    .GO_TO_BOTTOM_button {
        bottom: 14px;  /* 縮小30% */
    }
    `;
    document.head.appendChild(style);

    const goToTop = () => {
        window.scrollTo({
            top: 0,
            behavior: 'smooth'
        });
    }

    let bottomInterval;
    const startScrollingToBottom = () => {
        bottomInterval = setInterval(() => {
            window.scrollTo({
                top: document.body.scrollHeight,
                behavior: 'smooth'
            });
        }, 1000);
    }

    const stopScrollingToBottom = () => {
        clearInterval(bottomInterval);
    }

    const buttonTop = document.createElement('div');
    buttonTop.className = 'GO_TO_TOP_button';
    buttonTop.innerHTML = `
    <svg viewBox="0 0 1024 1024" version="1.1" xmlns="http://www.w3.org/2000/svg">
        <path d="M825.568 555.328l-287.392-289.28C531.808 259.648 523.488 256.576 515.2 256.64 514.08 256.544 513.12 256 512 256c-4.672 0-9.024 1.088-13.024 2.88-4.032 1.536-7.872 3.872-11.136 7.136l-259.328 258.88c-12.512 12.48-12.544 32.736-0.032 45.248 6.24 6.272 14.432 9.408 22.656 9.408 8.192 0 16.352-3.136 22.624-9.344L480 364.288V928c0 17.696 14.336 32 32 32s32-14.304 32-32V362.72l236.192 237.728c6.24 6.272 14.496 9.44 22.688 9.44s16.32-3.104 22.56-9.312C838.016 588.128 838.048 567.84 825.568 555.328z"/>
        <path d="M864 192H160C142.336 192 128 177.664 128 160s14.336-32 32-32h704c17.696 0 32 14.336 32 32S881.696 192 864 192z"/>
    </svg>`;

    const buttonBottom = document.createElement('div');
    buttonBottom.className = 'GO_TO_BOTTOM_button';
    buttonBottom.innerHTML = `
    <svg viewBox="0 0 1024 1024" version="1.1" xmlns="http://www.w3.org/2000/svg">
        <path d="M198.4 468.352l287.392 289.28c6.368 6.4 14.688 9.472 22.976 9.408 1.12 0.096 2.08 0.64 3.2 0.64 4.672 0 9.024-1.088 13.024-2.88 4.032-1.536 7.872-3.872 11.136-7.136l259.328-258.88c12.512-12.48 12.544-32.736 0.032-45.248-6.24-6.272-14.432-9.408-22.656-9.408-8.192 0-16.352 3.136-22.624 9.344L544 659.712V96c0-17.696-14.336-32-32-32s-32 14.304-32 32v565.28L243.808 423.552c-6.24-6.272-14.496-9.44-22.688-9.44s-16.32 3.104-22.56 9.312c-12.48 12.512-12.512 32.8-0.032 45.312z"/>
        <path d="M160 832h704c17.664 0 32 14.336 32 32s-14.336 32-32 32H160c-17.664 0-32-14.336-32-32s14.336-32 32-32z"/>
    </svg>`;

    let isScrollingToBottom = false;

    buttonTop.addEventListener('click', goToTop);

    buttonBottom.addEventListener('click', () => {
        if (isScrollingToBottom) {
            stopScrollingToBottom();
            buttonBottom.style.transform = 'scale(1)';
        } else {
            startScrollingToBottom();
            buttonBottom.style.transform = 'scale(1.1)';
        }
        isScrollingToBottom = !isScrollingToBottom;
    });

    buttonTop.style.display = 'none';
    buttonBottom.style.display = 'none';
    document.body.appendChild(buttonTop);
    document.body.appendChild(buttonBottom);

    let timer;
    window.addEventListener('scroll', () => {
        if (window.pageYOffset > 50) {
            buttonTop.style.opacity = '0.8';
            buttonTop.style.display = 'flex';
            buttonBottom.style.opacity = '0.8';
            buttonBottom.style.display = 'flex';
        } else if (window.pageYOffset === 0) {
            buttonTop.style.opacity = '0';
            buttonBottom.style.opacity = '0';
            setTimeout(() => {
                buttonTop.style.display = 'none';
                buttonBottom.style.display = 'none';
            }, 200);
        }
        clearTimeout(timer);
        timer = setTimeout(() => {
            buttonTop.style.opacity = '0';
            buttonBottom.style.opacity = '0';
            setTimeout(() => {
                buttonTop.style.display = 'none';
                buttonBottom.style.display = 'none';
            }, 200);
        }, 1800);
    });
})();