50个实用JS自定义函数（一）

1、原生JavaScript实现字符串长度截取
代码如下:

function cutstr(str, len) {
    var temp;
    var icount = 0;
    var patrn = /[^\x00-\xff]/;
    var strre = "";
    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
            }
            strre += temp
        } else {
            break
        }
    }
    return strre + "..."
}

2、原生JavaScript获取域名主机
代码如下:

function getHost(url) {
    var host = "null";
    if(typeof url == "undefined"|| null == url) {
        url = window.location.href;
    }
    var regex = /^\w+\:\/\/([^\/]*).*/;
    var match = url.match(regex);
    if(typeof match != "undefined" && null != match) {
        host = match[1];
    }
    return host;
}

3、原生JavaScript清除空格
代码如下:

String.prototype.trim = function() {
    var reExtraSpace = /^\s*(.*?)\s+$/;
    return this.replace(reExtraSpace, "$1")
}

4、原生JavaScript替换全部
代码如下:

String.prototype.replaceAll = function(s1, s2) {
    return this.replace(new RegExp(s1, "gm"), s2)
}

5、原生JavaScript转义html标签
代码如下:

function HtmlEncode(text) {
    return text.replace(/&/g, '&').replace(/\"/g, '"').replace(/</g, '<').replace(/>/g, '>')
}

6、原生JavaScript还原html标签
代码如下:

function HtmlDecode(text) {
    return text.replace(/&/g, '&').replace(/"/g, '\"').replace(/</g, '<').replace(/>/g, '>')
}

7、原生JavaScript时间日期格式转换
代码如下:

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
}

8、原生JavaScript判断是否为数字类型
代码如下:

function isDigit(value) {
    var patrn = /^[0-9]*$/;
    if (patrn.exec(value) == null || value == "") {
        return false
    } else {
        return true
    }
}

9、原生JavaScript设置cookie值
代码如下:

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;"
}

10、原生JavaScript获取cookie值
代码如下:

function getCookie(name) {
    var arr = document.cookie.match(new RegExp("(^| )" + name + "=([^;]*)(;|$)"));
    if (arr != null) return unescape(arr[2]);
    return null
}

11、原生JavaScript加入收藏夹
代码如下:

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")
        }
    }
}

12、原生JavaScript设为首页
代码如下:

function setHomepage() {
    if (document.all) {
        document.body.style.behavior = 'url(#default#homepage)';
        document.body.setHomePage('http://www.jq-school.com')
    } 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://www.jq-school.com')
    }
}

13、原生JavaScript判断IE6
代码如下:

var ua = navigator.userAgent.toLowerCase();
var isIE6 = ua.indexOf("msie 6") > -1;
if (isIE6) {
    try {
        document.execCommand("BackgroundImageCache", false, true)
    } catch(e) {}
}

14、原生JavaScript加载样式文件
代码如下:

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)
    }
}

15、原生JavaScript返回脚本内容
代码如下:

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;
}

16、原生JavaScript清除脚本内容
代码如下:

function stripscript(s) {
  return s.replace(/<script.*?>.*?<\/script>/ig, '');
}

17、原生JavaScript动态加载脚本文件
代码如下:

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. = false;
      scriptNode.onload = function () {
        scriptNode. = true;
        JSLOADED[src] = 1;
      };
      scriptNode.onreadystatechange = function () {
        if((scriptNode.readyState == 'loaded' || scriptNode.readyState == 'complete') && !scriptNode. {
          scriptNode. = true;
          JSLOADED[src] = 1;
        }
      };
    } else if(text){
      scriptNode.text = text;
    }
    document.getElementsByTagName('head')[0].appendChild(scriptNode);
  } catch(e) {}
}


18、原生JavaScript返回按ID检索的元素对象
代码如下:

function $(id) {
  return !id ? null : document.getElementById(id);
}

19、原生JavaScript返回浏览器版本内容
代码如下:

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;
}

20、原生JavaScript元素显示的通用方法
代码如下:

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' : '';
  }
}

21、原生JavaScript中有insertBefore方法,可惜却没有insertAfter方法?用如下函数实现
代码如下:

function insertAfter(newChild,refChild){
  var parElem=refChild.parentNode;
  if(parElem.lastChild==refChild){
    refChild.appendChild(newChild);
  }else{
    parElem.insertBefore(newChild,refChild.nextSibling);
  }
}

22、原生JavaScript中兼容浏览器绑定元素事件
代码如下:

function addEventSamp(obj,evt,fn){
  if (obj.addEventListener) {
    obj.addEventListener(evt, fn, false);
  }else if(obj.attachEvent){
    obj.attachEvent('on'+evt,fn);
  }
}

23、原生JavaScript光标停在文字的后面，文本框获得焦点时调用
代码如下:

function focusLast(){
  var e = event.srcElement;
  var r =e.createTextRange();
  r.moveStart('character',e.value.length);
  r.collapse(true);
  r.select();
}

24、原生JavaScript检验URL链接是否有效
代码如下:

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);
    }
  }
}

25、原生JavaScript格式化CSS样式代码
代码如下:

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 {\n\t$2");
  s = s.replace(/([^\s])\}([^\n]*)/g, "$1\n}\n$2");
  s = s.replace(/([^\s]);([^\s\}])/g, "$1;\n\t$2");
  return s;
}

26、原生JavaScript压缩CSS样式代码
代码如下:

function yasuoCss (s) {//压缩代码
  s = s.replace(/\/\*(.|\n)*?\*\//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];
}

27、原生JavaScript获取当前路径
代码如下:

var currentPageUrl = "";
if (typeof this.href === "undefined") {
    currentPageUrl = document.location.toString().toLowerCase();
}
else {
    currentPageUrl = this.href.toString().toLowerCase();
}

28、原生JavaScriptIP转成整型
代码如下:

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;
}

29、原生JavaScript整型解析为IP地址
代码如下:

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;
}

30、原生JavaScript实现checkbox全选与全不选
代码如下:

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;
    }
  }
}
注：移动篇 (31~40)
31、原生JavaScript判断是否移动设备
代码如下:

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;
}

32、原生JavaScript判断是否移动设备访问
代码如下:

function isMobileUserAgent(){
  return (/iphone|ipod|android.*mobile|windows.*phone|blackberry.*mobile/i.test(window.navigator.userAgent.toLowerCase()));
}

33、原生JavaScript判断是否苹果移动设备访问
代码如下:

function isAppleMobileDevice(){
  return (/iphone|ipod|ipad|Macintosh/i.test(navigator.userAgent.toLowerCase()));
}

34、原生JavaScript判断是否安卓移动设备访问
代码如下:

function isAndroidMobileDevice(){
  return (/android/i.test(navigator.userAgent.toLowerCase()));
}

35、原生JavaScript判断是否Touch屏幕
代码如下:

function isTouchScreen(){
  return (('ontouchstart' in window) || window.DocumentTouch && document instanceof DocumentTouch);
}

36、原生JavaScript判断是否在安卓上的谷歌浏览器
代码如下:

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;
}


37、原生JavaScript判断是否打开视窗
代码如下:

function isViewportOpen() {
  return !!document.getElementById('wixMobileViewport');
}

38、原生JavaScript获取移动设备初始化大小
代码如下:

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;
}

39、原生JavaScript获取移动设备最大化大小
代码如下:

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;
  }
}

40、原生JavaScript获取移动设备屏幕宽度
代码如下:

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;
}

41、原生JavaScript完美判断是否为网址
代码如下:

function IsURL(strUrl) {
    var regular = /^\b(((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)|(1\d\d)|([1-9]\d)|\d))\b(\/[-a-z0-9_:\@&?=+,.!\/~%\$]*)?)$/i
    if (regular.test(strUrl)) {
        return true;
    }
    else {
        return false;
    }
}

42、原生JavaScript根据样式名称检索元素对象
代码如下:

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
}

43、原生JavaScript判断是否以某个字符串开头
代码如下:

String.prototype.startWith = function (s) {
    return this.indexOf(s) == 0
}

44、原生JavaScript判断是否以某个字符串结束
代码如下:

String.prototype.endWith = function (s) {
    var d = this.length - s.length;
    return (d >= 0 && this.lastIndexOf(s) == d)
}

45、原生JavaScript返回IE浏览器的版本号
代码如下:

function getIE(){
    if (window.ActiveXObject){
        var v = navigator.userAgent.match(/MSIE ([^;]+)/)[1];
        return parseFloat(v.substring(0, v.indexOf(".")))
    }
    return false
}

46、原生JavaScript获取页面高度
代码如下:

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);
}

47、原生JavaScript获取页面scrollLeft
代码如下:

function getPageScrollLeft(){
  var a = document;
  return a.documentElement.scrollLeft || a.body.scrollLeft;
}

48、原生JavaScript获取页面可视宽度
代码如下:

function getPageViewWidth(){
  var d = document, a = d.compatMode == "BackCompat"
      ? d.body
      : d.documentElement;
  return a.clientWidth;
}

49、原生JavaScript获取页面宽度
代码如下:

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);
}

50、原生JavaScript获取页面scrollTop
代码如下:

function getPageScrollTop(){
  var a = document;
  return a.documentElement.scrollTop || a.body.scrollTop;
}