分享10个原生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, '&').replace(//"/g, '"').replace(/</g, '<').replace(/>/g, '>') }

6、还原html标签

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   } }