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记录一些js实用到码片段

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文章字数：1200,阅读全文大约需要4分钟

摘自今日头条，一些以后可能会用到的代码片段。

  1. 原生JavaScript实现字符串长度截取
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    function cutstr(str, len) {
     var temp;
     var icount = 0;
     var patrn = /[^\x00-\xff]/; // 匹配双字节字符(包括汉字在内)
     var strren = "";
     for (var i = 0; i < str.length; i++) {
       if (icount < len - 1) {
       temp = str.substr(i, 1);
       if (patrn.exec(temp) == null) {
       icount = icount + 1;
       } else {
       icount = icount + 2;
       }
       } else {
       break;
      }
      }
     return strre + "...";
    }
  2. 原生JavaScript获取域名主机
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    function getHost(url) {
     var host = "null";
     if (typeof url == undefined || url === null) {
     url = window.location.href;
     }
     var regex = /^w+://([^/]*).*/;
     var match = url.match(regex);
     if (typeof match != undefined && match != null) {
     host = match[1];
     }
     return host;
    }
  3. 原生JavaScript清除空格
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    String.prototype.trim = function() {
     var reExtraSpace = /^s*(.*?)s+$/;
     return this.replace(reExtraSpace, "$1");
    }
  4. 原生JavaScript替换全部
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    String.prototype.replaceAll = function(s1, s2) {
     return this.replace(new RegExp(s1, "gm"), s2);
    }
  5. 原生JavaScript转义html标签
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    function HtmlEncode(text) {
     return text.replace(/&/g, '&amp')
     .replace(/"/g, '&quot')
     .replace(/</g, '&lt')
     .replace(/>/g, '&gt');
    }
  6. 原生JavaScript还原html标签
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    function HtmlDecode(text) {
     return text.replace('&amp', /&/g)
     .replace('&quot', /"/g)
     .replace('&lt', /</g)
     .replace('&gt', />/g);
    }
    7. 原生JavaScript时间日期格式替换
    ```javascript
    Date.prototype.Format = function(formatStr) {
     var str = formatStr;
     var Week = ['日', '一', '二', '三', '四', '五', '六'];
     str = str.replace(/yyyy|YYYY/, this.getFullYear());
     str = str.replace(/yy|YY/, (this.getYear() % 100) > 9 ? (this.getYear() % 100).toString() : '0' + (this.getYear() % 100));
     str = str.replace(/MM/, (this.getMonth() + 1) > 9 ? (this.getMonth() + 1).toString() : '0' + (this.getMonth() + 1));
     str = str.replace(/M/g, (this.getMonth() + 1));
     str = str.replace(/w|W/g, Week[this.getDay()]);
     str = str.replace(/dd|DD/, this.getDate() > 9 ? this.getDate().toString() : '0' + this.getDate());
     str = str.replace(/d|D/g, this.getDate());
     str = str.replace(/hh|HH/, this.getHours() > 9 ? this.getHours().toString() : '0' + this.getHours());
     str = str.replace(/h|H/g, this.getHours());
     str = str.replace(/mm/, this.getMinutes() > 9 ? this.getMinutes().toString() : '0' + this.getMinutes());
     str = str.replace(/m/g, this.getMinutes());
     str = str.replace(/ss|SS/, this.getSeconds() > 9 ? this.getSeconds().toString() : '0' + this.getSeconds());
     str = str.replace(/s|S/g, this.getSeconds());
     return str
     }
  7. 原生JavaScript判断是否为数字类型
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    function isDigit(value) {
     var patrn = /^[0-9]*$/;
     if (patrn.exec(value) == null || value == "") {
     return false
     } else {
     return true
     }
    }
  8. 原生JavaScript设置cookie值
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    function setCookie(name, value, Hours) {
     var d = new Date();
     var offset = 8;
     var utc = d.getTime() + (d.getTimezoneOffset() * 60000);
     var nd = utc + (3600000 * offset);
     var exp = new Date(nd);
     exp.setTime(exp.getTime() + Hours * 60 * 60 * 1000);
     document.cookie = name + "=" + escape(value) + ";path=/;expires=" + exp.toGMTString() + ";domain=360doc.com;"
    }
  9. 原生JavaScript获取cookie值
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    function getCookie(name) {
     var arr = document.cookie.match(new RegExp("(^| )" + name + "=([^;]*)(;|$)"));
     if (arr != null) return unescape(arr[2]);
     return null
    }
  10. 原生JavaScript加入收藏夹
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    function AddFavorite(sURL, sTitle) {
     try {
     window.external.addFavorite(sURL, sTitle)
     } catch(e) {
     try {
     window.sidebar.addPanel(sTitle, sURL, "")
     } catch(e) {
     alert("加入收藏失败，请使用Ctrl+D进行添加")
     }
     }
    }
  11. 原生JavaScript设为首页
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    function setHomepage() {
     if (document.all) {
     document.body.style.behavior = 'url(#default#homepage)';
     document.body.setHomePage('http://***');
     } else if (window.sidebar) {
     if (window.netscape) {
     try {
     netscape.security.PrivilegeManager.enablePrivilege("UniversalXPConnect")
     } catch(e) {
     alert("该操作被浏览器拒绝，如果想启用该功能，请在地址栏内输入 about:config,然后将项 signed.applets.codebase_principal_support 值该为true")
     }
     }
     var prefs = Components.classes['@mozilla.org/preferences-service;1'].getService(Components.interfaces.nsIPrefBranch);
     prefs.setCharPref('browser.startup.homepage', 'http://***')
     }
    }
  12. 原生JavaScript判断IE6
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    var ua = navigator.userAgent.toLowerCase();
    var isIE6 = ua.indexOf("msie 6") > -1;
    if (isIE6) {
     try {
     document.execCommand("BackgroundImageCache", false, true)
     } catch(e) {}
    }
  13. 原生JavaScript加载样式文件
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    function LoadStyle(url) {
     try {
     document.createStyleSheet(url)
     } catch(e) {
     var cssLink = document.createElement('link');
     cssLink.rel = 'stylesheet';
     cssLink.type = 'text/css';
     cssLink.href = url;
     var head = document.getElementsByTagName('head')[0];
     head.appendChild(cssLink)
     }
    }
  14. 原生JavaScript返回脚本内容
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    function evalscript(s) {
     if(s.indexOf('<script') == -1) return s;
     var p = /<script[^>]*?>([^\x00]*?)</script>/ig;
     var arr = [];
     while(arr = p.exec(s)) {
     var p1 = /<script[^>]*?src="([^>]*?)"[^>]*?(reload="1")?(?:charset="([w-]+?)")?></script>/i;
     var arr1 = [];
     arr1 = p1.exec(arr[0]);
     if(arr1) {
     appendscript(arr1[1], '', arr1[2], arr1[3]);
     } else {
     p1 = /<script(.*?)>([^\x00]+?)</script>/i;
     arr1 = p1.exec(arr[0]);
     appendscript('', arr1[2], arr1[1].indexOf('reload=') != -1);
     }
     }
     return s;
    }
  15. 原生JavaScript清除脚本内容
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    function stripscript(s) {
     return s.replace(/<script.*?>.*?</script>/ig, '');
    }
  16. 原生JavaScript动态加载脚本文件
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    function appendscript(src, text, reload, charset) {
     var id = hash(src + text);
     if(!reload && in_array(id, evalscripts)) return;
     if(reload && $(id)) {
     $(id).parentNode.removeChild($(id));
     }
     
     evalscripts.push(id);
     var scriptNode = document.createElement("script");
     scriptNode.type = "text/javascript";
     scriptNode.id = id;
     scriptNode.charset = charset ? charset : (BROWSER.firefox ? document.characterSet : document.charset);
     try {
     if(src) {
     scriptNode.src = src;
     scriptNode.onloadDone = false;
     scriptNode.onload = function () {
     scriptNode.onloadDone = true;
     JSLOADED[src] = 1;
     };
     scriptNode.onreadystatechange = function () {
     if((scriptNode.readyState == 'loaded' || scriptNode.readyState == 'complete') && !scriptNode.onloadDone) {
     scriptNode.onloadDone = true;
     JSLOADED[src] = 1;
     }
     };
     } else if(text){
     scriptNode.text = text;
     }
     document.getElementsByTagName('head')[0].appendChild(scriptNode);
     } catch(e) {}
    }
  17. 原生JavaScript返回按ID检索的元素对象
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    function $(id) {
     return !id ? null : document.getElementById(id);
    }
  18. 原生JavaScript返回浏览器版本内容
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    function browserVersion(types) {
     var other = 1;
     for(i in types) {
     var v = types[i] ? types[i] : i;
     if(USERAGENT.indexOf(v) != -1) {
     var re = new RegExp(v + '(\/|\s)([\d\.]+)', 'ig');
     var matches = re.exec(USERAGENT);
     var ver = matches != null ? matches[2] : 0;
     other = ver !== 0 && v != 'mozilla' ? 0 : other;
     }else {
     var ver = 0;
     }
     eval('BROWSER.' + i + '= ver');
     }
     BROWSER.other = other;
    }
  19. 原生JavaScript元素显示的通用方法
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    function $(id) {
     return !id ? null : document.getElementById(id);
    }
    function display(id) {
     var obj = $(id);
     if(obj.style.visibility) {
     obj.style.visibility = obj.style.visibility == 'visible' ? 'hidden' : 'visible';
     } else {
     obj.style.display = obj.style.display == '' ? 'none' : '';
     }
    }
  20. 原生JavaScript中有insertBefore方法,可惜却没有insertAfter方法?用如下函数实现
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    function insertAfter(newChild, refChild) {
     var parElem = refChild.parentNode; 
     if(parElem.lastChild == refChild){ 
     refChild.appendChild(newChild); 
     }else{ 
     parElem.insertBefore(newChild, refChild.nextSibling); 
     } 
    }
  21. 原生JavaScript中兼容浏览器绑定元素事件
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    function addEventSamp(obj, evt, fn){ 
     if (obj.addEventListener) { 
     obj.addEventListener(evt, fn, false); 
     }else if(obj.attachEvent){ 
     obj.attachEvent('on' + evt, fn); 
     } 
    }
  22. 原生JavaScript光标停在文字的后面，文本框获得焦点时调用
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    function focusLast(){ 
     var e = event.srcElement; 
     var r =e.createTextRange(); 
     r.moveStart('character',e.value.length); 
     r.collapse(true); 
     r.select(); 
    }
  23. 原生JavaScript检验URL链接是否有效
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    function getUrlState(URL) { 
     var xmlhttp = new ActiveXObject("microsoft.xmlhttp"); 
     xmlhttp.Open("GET", URL, false); 
     try { 
     xmlhttp.Send(); 
     } catch(e) {
     
     } finally { 
     var result = xmlhttp.responseText; 
     if(result) { 
     if(xmlhttp.Status==200){ 
     return true; 
     }else{ 
     return false; 
     } 
     } else { 
     return false; 
     } 
     } 
    }
  24. 原生JavaScript格式化CSS样式代码
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    function formatCss(s){ //格式化代码
     s = s.replace(/s*([{}:;,])s*/g, "$1");
     s = s.replace(/;s*;/g, ";"); //清除连续分号
     s = s.replace(/,[s.#d]*{/g, "{");
     s = s.replace(/([^s]){([^s])/g, "$1 {
    	$2");
     s = s.replace(/([^s])}([^
    ]*)/g, "$1
    }
    $2");
     s = s.replace(/([^s]);([^s}])/g, "$1;
    	$2");
     return s;
    }
  25. 原生JavaScript压缩CSS样式代码
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    function yasuoCss (s) { //压缩代码
     s = s.replace(//*(.|
    )*?*//g, ""); //删除注释
     s = s.replace(/s*([{}:;,])s*/g, "$1");
     s = s.replace(/,[s.#d]*{/g, "{"); //容错处理
     s = s.replace(/;s*;/g, ";"); //清除连续分号
     s = s.match(/^s*(S+(s+S+)*)s*$/); //去掉首尾空白
     return (s == null) ? "" : s[1];
    }
  26. 原生JavaScript获取当前路径
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    var currentPageUrl = "";
    if (typeof this.href === undefined) {
     currentPageUrl = document.location.toString().toLowerCase();
    }
    else {
     currentPageUrl = this.href.toString().toLowerCase();
    }
  27. 原生JavaScript将IP地址转成整型
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    function _ip2int(ip){
     var num = 0;
     ip = ip.split(".");
     num = Number(ip[0]) * 256 * 256 * 256 + Number(ip[1]) * 256 * 256 + Number(ip[2]) * 256 + Number(ip[3]);
     num = num >>> 0;
     return num;
    }
  28. 原生JavaScript整型解析为IP地址
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    function _int2iP(num){
     var str;
     var tt = new Array();
     tt[0] = (num >>> 24) >>> 0;
     tt[1] = ((num << 8) >>> 24) >>> 0;
     tt[2] = (num << 16) >>> 24;
     tt[3] = (num << 24) >>> 24;
     str = String(tt[0]) + "." + String(tt[1]) + "." + String(tt[2]) + "." + String(tt[3]);
     return str;
    }
  29. 原生JavaScript实现checkbox全选与全不选
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    function checkAll() {
     var selectall = document.getElementById("selectall");
     var allbox = document.getElementsByName("allbox");
     if (selectall.checked) {
     for (var i = 0; i < allbox.length; i++) {
     allbox[i].checked = true;
     }
     } else {
     for (var i = 0; i < allbox.length; i++) {
     allbox[i].checked = false;
     }
     }
    }
  30. 原生JavaScript判断是否移动设备
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    function isMobile(){
     if (typeof this._isMobile === 'boolean'){
     return this._isMobile;
     }
     var screenWidth = this.getScreenWidth();
     var fixViewPortsExperiment = rendererModel.runningExperiments.FixViewport || rendererModel.runningExperiments.fixviewport;
     var fixViewPortsExperimentRunning = fixViewPortsExperiment && (fixViewPortsExperiment.toLowerCase() === "new");
     if(!fixViewPortsExperiment){
     if(!this.isAppleMobileDevice()){
     screenWidth = screenWidth/window.devicePixelRatio;
     }
     }
     var isMobileScreenSize = screenWidth < 600;
     var isMobileUserAgent = false;
     this._isMobile = isMobileScreenSize && this.isTouchScreen();
     return this._isMobile;
    }
  31. 原生JavaScript判断是否移动设备访问
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    function isMobileUserAgent() {
     return (/iphone|ipod|android.*mobile|windows.*phone|blackberry.*mobile/i.test(window.navigator.userAgent.toLowerCase()));
    }
  32. 原生JavaScript判断是否苹果移动设备访问
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    function isAppleMobileDevice() {
     return (/iphone|ipod|ipad|Macintosh/i.test(navigator.userAgent.toLowerCase()));
    }
  33. 原生JavaScript判断是否安卓移动设备访问
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    function isAndroidMobileDevice(){
     return (/android/i.test(navigator.userAgent.toLowerCase()));
    }
  34. 原生JavaScript判断是否Touch屏幕
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    function isTouchScreen() {
     return (('ontouchstart' in window) || window.DocumentTouch && document instanceof DocumentTouch);
    }
  35. 原生JavaScript判断是否在安卓上的谷歌浏览器
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    function isNewChromeOnAndroid(){
     if(this.isAndroidMobileDevice()){
     var userAgent = navigator.userAgent.toLowerCase();
     if((/chrome/i.test(userAgent))){
     var parts = userAgent.split('chrome/');
     var fullVersionString = parts[1].split(" ")[0];
     var versionString = fullVersionString.split('.')[0];
     var version = parseInt(versionString);
     if(version >= 27){
     return true;
     }
     }
     }
     return false;
    }
  36. 原生JavaScript判断是否打开视窗
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    function isViewportOpen() {
     return !!document.getElementById('wixMobileViewport');
    }
  37. 原生JavaScript获取移动设备初始化大小
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    function getInitZoom() {
     if(!this._initZoom) {
     var screenWidth = Math.min(screen.height, screen.width);
     if(this.isAndroidMobileDevice() && !this.isNewChromeOnAndroid()) {
     screenWidth = screenWidth / window.devicePixelRatio;
     }
     this._initZoom = screenWidth /document.body.offsetWidth;
     }
     return this._initZoom;
    }
  38. 原生JavaScript获取移动设备最大化大小
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    function getZoom(){
     var screenWidth = (Math.abs(window.orientation) === 90) ? Math.max(screen.height, screen.width) : Math.min(screen.height, screen.width);
     if(this.isAndroidMobileDevice() && !this.isNewChromeOnAndroid()){
     screenWidth = screenWidth/window.devicePixelRatio;
     }
     var FixViewPortsExperiment = rendererModel.runningExperiments.FixViewport || rendererModel.runningExperiments.fixviewport;
     var FixViewPortsExperimentRunning = FixViewPortsExperiment && (FixViewPortsExperiment === "New" || FixViewPortsExperiment === "new");
     if(FixViewPortsExperimentRunning){
     return screenWidth / window.innerWidth;
     }else{
     return screenWidth / document.body.offsetWidth;
     }
    }
  39. 原生JavaScript获取移动设备屏幕宽度
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    function getScreenWidth(){
     var smallerSide = Math.min(screen.width, screen.height);
     var fixViewPortsExperiment = rendererModel.runningExperiments.FixViewport || rendererModel.runningExperiments.fixviewport;
     var fixViewPortsExperimentRunning = fixViewPortsExperiment && (fixViewPortsExperiment.toLowerCase() === "new");
     if(fixViewPortsExperiment){
     if(this.isAndroidMobileDevice() && !this.isNewChromeOnAndroid()){
     smallerSide = smallerSide/window.devicePixelRatio;
     }
     }
     return smallerSide;
    }
  40. 原生JavaScript完美判断是否为网址
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    function IsURL(strUrl) {
     var regular = /^(((https?|ftp)://)?[-a-z0-9]+(.[-a-z0-9]+)*.(?:com|edu|gov|int|mil|net|org|biz|info|name|museum|asia|coop|aero|[a-z][a-z]|((25[0-5])|(2[0-4]d)|(1dd)|([1-9]d)|d))(/[-a-z0-9_:@&?=+,.!/~%$]*)?)$/i
     if (regular.test(strUrl)) {
     return true;
     }
     else {
     return false;
     }
    }
  41. 原生JavaScript根据样式名称检索元素对象
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    function getElementsByClassName(name) {
     var tags = document.getElementsByTagName('*') || document.all;
     var els = [];
     for (var i = 0; i < tags.length; i++) {
     if (tags[i].className) {
     var cs = tags[i].className.split(' ');
     for (var j = 0; j < cs.length; j++) {
     if (name == cs[j]) {
     els.push(tags[i]);
     break;
     }
     }
     }
     }
     return els;
    }
  42. 原生JavaScript判断是否以某个字符串开头
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    String.prototype.startWith = function (s) {
     return this.indexOf(s) == 0;
    }
  43. 原生JavaScript判断是否以某个字符串结束
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    String.prototype.endWith = function (s) {
     var d = this.length - s.length;
     return (d >= 0 && this.lastIndexOf(s) == d);
    }
  44. 原生JavaScript返回IE浏览器的版本号
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    function getIE(){
     if (window.ActiveXObject){
     var v = navigator.userAgent.match(/MSIE ([^;]+)/)[1];
     return parseFloat(v.substring(0, v.indexOf(".")));
     }
     return false;
    }
  45. 原生JavaScript获取页面高度
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    function getPageHeight() {
     var g = document, a = g.body, f = g.documentElement, d = g.compatMode == "BackCompat"
     ? a
     : g.documentElement;
     return Math.max(f.scrollHeight, a.scrollHeight, d.clientHeight);
    }
  46. 原生JavaScript获取页面scrollLeft
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    function getPageScrollLeft(){
     var a = document;
     return a.documentElement.scrollLeft || a.body.scrollLeft;
    }
  47. 原生JavaScript获取页面可视宽度
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    function getPageViewWidth(){
     var d = document, a = d.compatMode == "BackCompat"
     ? d.body
     : d.documentElement;
     return a.clientWidth; // 可视宽度为clientWidth
    }
  48. 原生JavaScript获取页面宽度
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    // 考虑带滚动条的全部宽度
    function getPageWidth(){
     var g = document, a = g.body, f = g.documentElement, d = g.compatMode == "BackCompat"
     ? a
     : g.documentElement;
     return Math.max(f.scrollWidth, a.scrollWidth, d.clientWidth);
    }
  49. 原生JavaScript获取页面scrollTop
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    function getPageScrollTop(){
     var a = document;
     return a.documentElement.scrollTop || a.body.scrollTop;
    }