@writ/utils/back-top.js

My tool kit

'use strict';

/**
 * 返回顶部的通用方法
 * @param {HTMLElement} button 
 */
export default function backTop(button) {
    var d = document.documentElement;
    var b = document.body;

    window.onscroll = set;
    button.style.display = "none";
    button.onclick = function onClick() {
        button.style.display = "none";
        window.onscroll = null;
        var timer = setInterval(function () {
            d.scrollTop -= Math.ceil((d.scrollTop + b.scrollTop) * 0.1);
            b.scrollTop -= Math.ceil((d.scrollTop + b.scrollTop) * 0.1);
            if (d.scrollTop + b.scrollTop <= 0) {
                clearInterval(timer);
                window.onscroll = set;
            }
        }, 10);
    };

    function set() {
        button.style.display = d.scrollTop + b.scrollTop > 100 ? "block" : "none";
    }
}