分享10个原生JavaScript技巧_javascript技巧

1、实现字符串长度截取

 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、获取域名主机

 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、清除空格

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

4、替换全部

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

5、转义html标签

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

6、还原html标签

复制代码 代码如下:

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

7、时间日期格式转换

 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、判断是否为数字类型

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

9、设置cookie值

 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、获取cookie值

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

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