/*
* HeiGoBackTop.js V1.0.5
* @author hei-jack
* @link https://github.com/hei-jack/HeiGoBackTop/
* Probably the most beautiful back to top widget
* 可能是最漂亮的返回顶部小插件
* first: GMT2021-07-22
* update: GMT2025-03-08
*
*/
; (function (global) {
"use strict";
var instance;
//构造函数
function HeiGoBackTop(mode, el, speed, distance, smooth) {
if (instance) {
return instance;
}
instance = this;
this.mode = mode === undefined ? 0 : mode;
this.el = el === undefined ? '#__go-back-top' : el;
this.realScrollEle = null;
this.iframe = null;
this.speed = speed === undefined ? 500 : speed;
this.distance = distance === undefined ? 100 : distance;
this.smooth = smooth === undefined ? true : smooth;
this.show_height = 400;
this.flag = false;
this.show_flag = false;
this.first_scroll_flag = false;
this.find_scroll_ele_flag = false;
this.width = '150px';
this.height = '40px';
this.bottom = '5%';
this.right = '5%';
this.text = '返回顶部';
this.text_color = '#fff';
this.radius = '40px';
this.themes = 0;
this.color = 'linear-gradient(to right,#6966ff,#37e2d3,#63e8dd,#ccff66)';
this.shadow = '0 4px 15px 0 rgba(41, 163, 163,0.75)';
this.version = 'V1.0.5';
this.home = 'https://github.com/hei-jack/HeiGoBackTop/';
//页面加载结束才进行初始化 没有必要执行实时载入
this.onLoad(this);
};
//拓展方法
HeiGoBackTop.prototype = {
constructor: HeiGoBackTop,
//钩子回调
hook: function (func) {
return func === undefined ? false : this.callBack(func.bind(this));
},
//beforeCreate 初始化之前执行
onBeforeCreate: function (func) {
this.beforeCreate = func;
},
//初始化结束事件
onAfterCreate: function (func) {
this.afterCreate = func;
},
onShow: function (func) {
this.show = func;
},
onHide: function (func) {
this.hide = func;
},
onClick: function (func) {
this.click = func;
},
//回调
callBack: function (func) {
return func();
},
//初始化方法
init: function () {
this.showVersion();
var notHtmlOrBody = !this.isRealScrollHtmlOrBody();
// 先执行一次 获取html,body的可滚动距离
if (notHtmlOrBody) {
setTimeout(function () {
// 延迟3秒执行 可能为渐进时网站 需要读取api再渲染
// 不是html或body为实际滚动元素 则寻找实际滚动元素
this.realScrollEle = this.findMainScrollingElement();
}.bind(this), 3000);
}
this.hook(this.beforeCreate);
this.unset('onBeforeCreate', null);
this.unset('beforeCreate');
//检查参数合法性
if (!this.checkArgs()) throw (new Error('arguments is error!'));
this.unset('checkNum', null);
this.unset('checkEl', null);
this.unset('checkArgs', null);
//初始化按钮
this.createBtn();
this.unset('createBtn', null);
this.unset('unsetUseless', null);
//绑定自定义鼠标滑动事件到全局滑动事件
this.bindOn(window, 'scroll', this.throttle(this.checkBtn.bind(this), 100), notHtmlOrBody);
this.bindOn(window, 'scroll', this.scroll, notHtmlOrBody);
this.controller();
this.unset('controller', null);
this.hook(this.afterCreate);
this.unset('onAfterCreate', null);
this.unset('afterCreate');
this.unset('bindOn', null);
this.unset('addEventListener', null);
this.unset('isBrowser', null);
this.unset('onLoad', null);
},
//检查参数
checkArgs: function () {
if (this.checkNum(this.mode)) return false;
if (this.mode > 3 || this.mode < 0) return false;
if (this.checkNum(this.speed) || this.speed <= 0) return false;
if (this.checkNum(this.distance) || this.distance <= 0) return false;
if (this.checkEl(this.el)) return false;
return true
},
//检查参数类型是否为数字
checkNum: function (arg) {
return typeof (arg) !== 'number';
},
//检查参数类型是否为不为0 且包含#号的字符串
checkEl: function (arg) {
return typeof (arg) !== 'string' || arg.length === 0 || arg.indexOf('#') === -1;
},
//创建按钮
createBtn: function () {
//如果不是初始元素id 说明用户自定义挂载元素
if (this.el !== '#__go-back-top') {
this.el = this.el.replace('#', '');
if (document.getElementById(this.el)) {
this.btn = document.getElementById(this.el);
this.unsetUseless();
return false
}
//挂载元素id没有发现 直接抛出错误
throw (new Error('element is error!'));
}
var iframeW = parseInt(this.width.replace("px", "")) + 20;
var iframeH = parseInt(this.height.replace("px", "")) + 40;
var style_text = '#__go-back-top{display:none;position:fixed;width:' + iframeW + 'px;height:' + iframeH + 'px;bottom:' + this.bottom + ';right:' + this.right + ';z-index:2147483647;border:0;outline:0;background: transparent;}';
var style_el = document.createElement('style');
var style_node = document.createTextNode(style_text);
style_el.appendChild(style_node);
document.body.appendChild(style_el);
var iframe = document.createElement('iframe');
iframe.setAttribute('id', this.el.replace('#', ''));
iframe.src = 'about:blank';
iframe.frameborder = "0";
iframe.allowtransparency = "true";
document.body.appendChild(iframe);
this.iframe = iframe;
var iframeDocument = iframe.contentDocument || iframe.contentWindow.document;
var style_text_btn = 'html,body{padding:0;margin:0;background:transparent;}#__go-back-top{width:100vw;height:100vh;display:flex;align-items:center;justify-content:center;align-content:center;background:transparent;}.__go-back-btn{width:' + this.width + ';height:' + this.height + ';background:' + this.color + ';background-size: 300% 100%;cursor: pointer;border:none;border-radius:' + this.radius + ';box-shadow:' + this.shadow + ';color:' + this.text_color + ';outline:none;letter-spacing:2px;font-weight:600;font-family: "YouYuan","Microsoft YaHei","SimHei","SimSun","Arial",sans-serif;transition: all .4s ease-in-out;moz-transition: all .4s ease-in-out;-o-transition: all .4s ease-in-out;-webkit-transition: all .4s ease-in-out;}.__go-back-btn:hover{background-position: 100% 0%;moz-transition: all .4s ease-in-out;-o-transition: all .4s ease-in-out;-webkit-transition: all .4s ease-in-out;transition: all .4s ease-in-out;}.__go-back-btn:focus{border:none;outline:none;}.go-back-top-themes1{background-image:linear-gradient(to right,#25aae1,#40e495,#30dd8a,#2bb673);box-shadow:0 4px 15px 0 rgba(49,196,190,0.75);}.go-back-top-themes2{background-image:linear-gradient(to right,#f5ce62,#e43603,#fa7199,#e85a19);box-shadow:0 4px 15px 0 rgba(229,66,10,0.75);}.go-back-top-themes3{background-image:linear-gradient(to right,#667eea,#764ba2,#6B8DD6,#8E37D7);box-shadow:0 4px 15px 0 rgba(116,79,168,0.75);}.go-back-top-themes4{background-image:linear-gradient(to right,#fc6076,#ff9a44,#ef9d43,#e75516);box-shadow:0 4px 15px 0 rgba(252,104,110,0.75);}.go-back-top-themes5{background-image:linear-gradient(to right,#0ba360,#3cba92,#30dd8a,#2bb673);box-shadow:0 4px 15px 0 rgba(23,168,108,0.75);}.go-back-top-themes6{background-image:linear-gradient(to right,#009245,#FCEE21,#00A8C5,#D9E021);box-shadow:0 4px 15px 0 rgba(83,176,57,0.75);}.go-back-top-themes7{background-image:linear-gradient(to right,#6253e1,#852D91,#A3A1FF,#F24645);box-shadow:0 4px 15px 0 rgba(126,52,161,0.75);}.go-back-top-themes8{background-image:linear-gradient(to right,#29323c,#485563,#2b5876,#4e4376);box-shadow:0 4px 15px 0 rgba(45,54,65,0.75);}.go-back-top-themes9{background-image:linear-gradient(to right,#25aae1,#4481eb,#04befe,#3f86ed);box-shadow:0 4px 15px 0 rgba(65,132,234,0.75);}.go-back-top-themes10{background-image:linear-gradient(to right,#ed6ea0,#ec8c69,#f7186a,#FBB03B);box-shadow:0 4px 15px 0 rgba(236,116,149,0.75);}.go-back-top-themes11{background-image:linear-gradient(to right,#eb3941,#f15e64,#e14e53,#e2373f);box-shadow:0 5px 15px rgba(242,97,103,.4);}';
var style_el_btn = iframeDocument.createElement('style');
var style_node_btn = iframeDocument.createTextNode(style_text_btn);
style_el_btn.appendChild(style_node_btn);
iframeDocument.body.appendChild(style_el_btn);
var div = document.createElement('div');
div.setAttribute('id', this.el.replace('#', ''));
var btn = document.createElement('button');
//设置主题  为0是默认主题 只有默认主题允许更改样式
this.themes === 0 ? btn.setAttribute('class', this.el.replace('#', '').replace('top', 'btn')) : btn.setAttribute('class', this.el.replace('#', '').replace('top', 'btn') + ' go-back-top-themes' + this.themes);
var btn_name = document.createTextNode(this.text);
btn.appendChild(btn_name);
div.appendChild(btn);
iframeDocument.body.appendChild(div);
this.btn = btn;
//创建结束 销毁已经没用的属性
this.unsetUseless();
},
showBtn: function () {
if (!this.show_flag) {
if (this.iframe) {
this.iframe.style.cssText = 'display:block';
}
this.btn.style.cssText = 'display:block';
this.hook(this.show);
this.show_flag = true;
}
},
hideBtn: function () {
if (this.show_flag) {
if (this.iframe) {
this.iframe.style.cssText = 'display:none';
}
this.btn.style.cssText = 'display:none';
this.hook(this.hide);
this.show_flag = false;
}
},
//载入方法 在页面加载结束后开始执行初始化工作
onLoad: function (self) {
if (!this.isBrowser()) throw (new Error('The current environment is not the browser!'));
if (this.isIE() && this.getIEVersion() < 9) throw (new Error('HeiGoBackTop does not support ie 9 the following browsers!'));
this.bindOn(window, 'load', self.init);
},
//当滑动事件发生时
onScroll: function (func) {
this.scroll = func;
},
//绑定元素事件
bindOn: function (el, event, func, useCapture) {
if (func === undefined) return false;
this.addEventListener(el, event, func.bind(this), useCapture)
},
//获取页面滚动的距离
getScrollTop: function () {
if (this.realScrollEle) {
return this.realScrollEle.scrollTop;
}
return document.documentElement.scrollTop || document.body.scrollTop;
},
//检查按钮何时显示和隐藏
checkBtn: function (event) {
if (!this.isRealScrollHtmlOrBody()) {
if (!this.first_scroll_flag) {
// 在用户第一次滚动的时候再来获取一边真实滚动元素
this.realScrollEle = this.findMainScrollingElement();
}
if (!this.realScrollEle.isConnected) {
// 真实滚动旧元素已经被移除 则重新寻找
this.realScrollEle = this.findMainScrollingElement();
}
// 如果用户滚动的元素和旧的真实滚动元素不一致
if (event.target !== this.realScrollEle) {
/*
// 判断谁的区域更大
var targetRect = event.target.getBoundingClientRect();
var rect = this.realScrollEle.getBoundingClientRect();
// 宽度优先法则 理论上主要滚动区域宽度都会占主体比较多的区域 而侧边栏或者其他区域虽然也可以滚动 但是区域会更小
if (targetRect.width >= rect.width) {
//直接记录
this.realScrollEle = event.target;
}
*/
// 滚动优先法则 用户滚动的是哪个区域 则点击按钮返回哪个区域的顶部
this.realScrollEle = event.target;
}
}
this.first_scroll_flag = true;
this.getScrollTop() > this.show_height ? this.showBtn() : this.hideBtn();
},
//绑定元素事件兼容处理函数
addEventListener: function (el, type, fn, useCapture) {
if (el.addEventListener) {
el.addEventListener(type, fn, useCapture ? true : false);
} else if (el.attachEvent) {
el.attachEvent('on' + type, fn);
} else {
return false;
}
},
//展示版本信息
showVersion: function () {
this.isIE() ? console.log("HeiGoBackTop " + this.version + ' ' + this.home) : console.log("\n\n %c HeiGoBackTop " + this.version + " %c " + this.home + " \n\n", "color: #fff; background: linear-gradient(90deg, #8080ff, #ff99ff); padding:5px 1px;", "background: linear-gradient(90deg,#ffccff,#80ffd4); padding:5px 0px;")
},
//模式分发控制器
controller: function () {
switch (this.mode) {
case 0:
this.bindOn(this.btn, 'click', this.goBackTop);
break;
case 1:
this.bindOn(this.btn, 'click', this.goDown);
break;
case 2:
this.bindOn(this.btn, 'click', this.goBackTopSlow);
break;
case 3:
this.bindOn(this.btn, 'click', this.goDownSlow)
}
},
//返回顶部
goBackTop: function () {
// 如果开启平滑模式
if (this.smooth) {
this.scrollToSmooth(0);
} else {
this.setScrollTop(0);
}
//滑动结束钩子
this.hook(this.scrollOver);
},
//慢滑到顶部
goBackTopSlow: function () {
this.scrollSpeed(this.getScrollTop(), 0);
},
//跳转底部
goDown: function () {
// 如果开启平滑模式
if (this.smooth) {
this.scrollToSmooth(this.getScrollHeight());
} else {
this.setScrollTop(this.getScrollHeight());
}
this.hook(this.scrollOver)
},
//慢滑到底部
goDownSlow: function () {
this.scrollSpeed(this.getScrollTop(), this.getScrollHeight());
},
/*
* 滑动方法
* @param number start 开始滑动位置
* @param number end 结束滑动位置
*
*/
scrollSpeed: function (start, end) {
//防止重复点击导致定时器多次调用
if (this.flag) return false;
this.flag = true;
var timer = null;
if (end === 0) {
//如果是滑动到顶部
timer = setInterval(function () {
var scroll_top = this.getScrollTop();
if (scroll_top >= this.distance) {
start -= this.distance;
this.setScrollTop(start);
} else {
if (scroll_top === 0) {
this.flag = false;
clearInterval(timer);
this.hook(this.scrollOver);
} else {
this.setScrollTop(0);
}
}
}.bind(this), this.speed);
} else {
//如果是滑动到底部
timer = setInterval(function () {
//getLast方法获取滚动条距离底部还剩多少距离 如果大于0 说明未到达底部 只管继续滑动即可
//向下取整 修复个别浏览器还剩余0.3左右的问题
if (Math.floor(this.getLast()) > 0) {
start += this.distance;
this.setScrollTop(start);
} else {
this.flag = false;
this.setScrollTop(end);
clearInterval(timer);
this.hook(this.scrollOver);
}
}.bind(this), this.speed);
}
},
// 平滑的滚动
scrollToSmooth: function (target) {
//  IE和safari不支持 options.behavior："smooth"
// 目标位置
var targetPosition = target;
// 开始滚动位置
var startPosition = this.getScrollTop();
try {
if (this.realScrollEle) {
this.realScrollEle.scrollTo({
top: targetPosition,
behavior: 'smooth'
});
return;
}
//如果出现异常 说明不支持behavior: 'smooth'
global.scrollTo({
top: targetPosition,
behavior: 'smooth'
});
} catch (e) {
var distance = targetPosition - startPosition;
var duration = 500; // 滚动持续时间，单位为毫秒
var startTime = null;
function animation(currentTime) {
if (startTime === null) startTime = currentTime;
var timeElapsed = currentTime - startTime;
var run = ease(timeElapsed, startPosition, distance, duration);
this.realScrollEle ? realScrollEle.scrollTop(0, run) : global.scrollTo(0, run);
if (timeElapsed < duration) global.requestAnimationFrame(animation);
}
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;
}
global.requestAnimationFrame(animation);
}
},
//设置当前滚动所在高度
setScrollTop: function (height) {
if (this.realScrollEle) {
return this.realScrollEle.scrollTop = height;
}
//处理兼容性问题
document.documentElement.scrollTop ? document.documentElement.scrollTop = height : document.body.scrollTop = height;
},
//获取滚动条高度 即可滚动的高度
getScrollHeight: function () {
if (this.realScrollEle) {
return this.realScrollEle.scrollHeight;
}
//兼容标准模式 strict mode 和 混杂模式 quirks mode
return document.compatMode === 'CSS1Compat' ? document.documentElement.scrollHeight : document.body.scrollHeight;
},
/*
* 销毁属性和方法
* @param string key 属性或方法名称
* @param set 可选参数 传入除undefined任意值则说明是方法 不传表示属性
*/
unset: function (key, set) {
if (set === undefined) {
delete this[key];
} else {
//ie不支持delete方法
this.isIE() && this.getIEVersion() <= 10 ? this[key] = undefined : this.__proto__[key] = undefined;
}
},
unsetUseless: function () {
this.unset('el');
this.unset('width');
this.unset('height');
this.unset('top');
this.unset('right');
this.unset('text');
this.unset('text_color');
this.unset('radius');
this.unset('themes');
this.unset('color');
this.unset('shadow')
},
//获取当前滚动条所在位置到页面底部还剩多少距离
getLast: function () {
var margin_bot = 0;
if (this.realScrollEle) {
margin_bot = this.realScrollEle.scrollHeight - this.realScrollEle.scrollTop - this.realScrollEle.clientHeight;
return margin_bot;
}
if (document.compatMode === "CSS1Compat") {
margin_bot = document.documentElement.scrollHeight - (document.documentElement.scrollTop + document.body.scrollTop) - document.documentElement.clientHeight;
} else {
margin_bot = document.body.scrollHeight - document.body.scrollTop - document.body.clientHeight;
}
return margin_bot;
},
//滑动结束执行事件
onScrollOver: function (func) {
this.scrollOver = func;
},
//判断当前浏览器是否为safari
isSafari: function () {
return (/Safari/.test(navigator.userAgent) && !/Chrome/.test(navigator.userAgent));
},
//获取当前浏览器是否为ie
isIE: function () {
if (!!window.ActiveXObject || "ActiveXObject" in window) return true;
return false;
},
//获取当前ie版本号
getIEVersion: function () {
var ua = navigator.userAgent;
//如果不是ie浏览器 设置初始值0
var ver = 0;
if (ua) {
if (ua.match(/MSIE\s+([\d]+)\./i)) {
//其他ie版本
ver = RegExp.$1;
} else if (ua.match(/Trident.*rv\s*:\s*([\d]+)\./i)) {
//ie11
ver = RegExp.$1;
}
}
return parseInt(ver);
},
//获取当前运行环境是否为浏览器
isBrowser: function () {
return typeof (window) === "undefined" ? false : true;
},
// 寻找实际滚动的是哪个元素 部分网站 实际滚动的区域是其他元素 例如vue之类可能滚动的是app元素 很多ai聊天网站滚动的下面布局元素
findMainScrollingElement: function () {
if (this.find_scroll_ele_flag) {
return;
}
this.find_scroll_ele_flag = true;
var bestCandidate = null;
var maxArea = 0;
var queue = [document.body]; // 从 body 开始层级遍历
while (queue.length > 0) {
var node = queue.shift();
// 检查当前节点是否可滚动
if (node.scrollHeight > node.clientHeight && window.getComputedStyle(node).overflowY !== 'hidden') {
var rect = node.getBoundingClientRect();
var area = rect.width * rect.height;
// 选择可视区域最大的可滚动元素
if (area > maxArea) {
maxArea = area;
bestCandidate = node;
}
}
// 将子节点加入队列
var children = node.children;
for (let i = 0; i < children.length; i++) {
queue.push(children[i]);
}
}
this.find_scroll_ele_flag = false;
// 如果没有找到可滚动元素，则返回 documentElement
return bestCandidate || document.documentElement;
},
// 判断真实滚动元素是否为html或body
isRealScrollHtmlOrBody: function () {
return document.documentElement.clientHeight < document.documentElement.scrollHeight || document.body.clientHeight < document.body.scrollHeight
},
// 节流函数
throttle: function (func, wait) {
var timer = null;
var startTime = Date.now();
return function () {
var curTime = Date.now();
var remaining = wait - (curTime - startTime);
var context = this;
var args = arguments;
clearTimeout(timer);
if (remaining <= 0) {
func.apply(context, args);
startTime = Date.now();
} else {
timer = setTimeout(function () {
func.apply(context, args);
}, remaining);  // 如果小于wait 保证在差值时间后执行
}
}
}
};
if (typeof module !== 'undefined' && module.exports) {
module.exports = HeiGoBackTop;
} else if (typeof define === 'function') {
define(function () {
return HeiGoBackTop;
})
} else {
// 避免重复挂载
if (!global.HeiGoBackTop) {
global.HeiGoBackTop = HeiGoBackTop;
}
}
})(this);