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JS实用技巧手记（二）

2018-06-17 19:23 更新

本系列文章旨在记录一些实用的javascript技巧，既可以作为一个知识的积累，又可以作为闲暇时打发时间写写代码的记录。同时也方便日后翻阅~

1. 实现字符串长度截取并在结尾添加…

function cutstr(str, len) {

var temp;

var icount = 0;

var patrn = /[^\x00-\xff]/; //表示汉字或者全角，即ASCII 编码不在0-255的字符

var strre = "";

for (var i = 0; i < str.length; i++) {

if (icount < len) {

// 每次截取一个字符

temp = str.substr(i, 1);

if (patrn.exec(temp) == null) {

// 如果是英文、半角

icount = icount + 1

} else {

// 如果是中文、全角

icount = icount + 2

}

// 字符串连接

strre += temp

} else {

break

}

return strre + "..."

}

// demo:

cutstr("xuanfeng", 2) //xu...

cutstr("轩枫阁", 3) //轩枫...

2. 获取主域名

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;

}

// demo:

getHost("http://www.xuanfengge.com/page/2") //www.xuanfengge.com

3. 清除左右空格

String.prototype.trim=function(){

　　return this.replace(/(^\s*)|(\s*$)/g, "");

}

String.prototype.ltrim=function(){

　　return this.replace(/(^\s*)/g,"");

}

String.prototype.rtrim=function(){

　　return this.replace(/(\s*$)/g,"");

}

// demo:

" xuanfeng ".trim() //xuanfeng

" xuanfengge".ltrim() //xuanfengge

"chrislee ".rtrim() //chrislee

4. 替换全部

String.prototype.replaceAll = function(s1, s2) {

return this.replace(new RegExp(s1, "gm"), s2)

}

// demo:

"哈哈哈".replaceAll('哈','呵') //呵呵呵

5. 转义html标签

function HtmlEncode(text) {

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

}

// demo:

HtmlEncode("<html></html>"); //<html></html>

6. 还原html标签

function HtmlDecode(text) {

return text.replace(/&/g, '&').replace(/"/g, '\"').replace(/</g, '<').replace(/>/g, '>')

}

// demo:

HtmlDecode("<html></html>"); //<html></html>

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;

}

// demo:

var date = new Date();

date.Format("YYYY-M-D"); //2013-5-8

date.Format("YYYY-MM-DD"); //2013-11-08

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

}

// demo:

isDigit("sdf"); //false

isDigit(12); //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=xuanfengge.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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