正则表达式

每一个正则表达式都是由元字符和修饰符组成的

元字符：d

常用的元字符：

:代表转义符
^:以某一个元字符开始
$:以某一个元字符结尾

.：除了 以外的任意字符，去除换行符

：换行符

()：分组

[^1|3]:除了1和3的其他

[.]：确定是一个点

D:除了数字以外的其他字符

：匹配一个边界符

w：数字，字母，下划线的任意一个字符[0-9a-zA-Z_]

s：匹配一个空白符，一个制表符（tab键）,空格，换页符

量词元字符：6个

*：代表出现次数的元字符，表示出现0到多次，0，1，2，3，可以不出现

+:出现1到多次

？：出现0或者一次

{n}:出现n次

{n,}:出现n到多次

{n，m}:出现n到m次

d:代表0-9的数字，D：代表

修饰符：

g:全局global，全局匹配

i：忽略大小写匹配

m:多行匹配

//exec

var reg=/d+?/g;
var str="fgwhfek29311bjfy49857311p5283ywe7ty";
var ary=[];
var res=reg.exec(str);
while(res){
ary.push(res[0]);
res=reg.exec(str);
}
console.log(ary);

 ？：量词取消正则捕获的贪婪性

//match

console.log('-------');
var reg=/d+?/g;
var str="fgwhfek29311bjfy49857311p5283ywe7ty";
var ary=[];
var res=str.match(reg);

var reg=/^(d{2})(d{4})(d{4})(d{2})(d{2})(?:d{2})(d)(d|X)$/;
console.log(reg.exec('412420198309102342'));

"？:"：只匹配不捕获

var reg=/^(d{2})(d{4})(d{4})(d{2})(d{2})(?:d{2})(?:d)(?:d|X)$/;
console.log(reg.exec('412420198309102342'));
var reg=/^(d{2})(d{4})(d{4})(d{2})(d{2})(?:d{2})(?:d)(?:d|X)$/;
console.log('412420198309102342'.match(reg));
var reg1=/qiqi(d+)/g;
var str="qiqi123qiqi0998qiqi8239";
console.log(reg1.exec(str));
console.log(reg1.exec(str));
console.log(reg1.exec(str));
console.log(str.match(reg1));
/*
(6) ["412420198309102342", "41", "2420", "1983", "09", "10", index: 0, input: "412420198309102342"]
["412420198309102342", "41", "2420", "1983", "09", "10", index: 0, input: "412420198309102342"]
["qiqi123", "123", index: 0, input: "qiqi123qiqi0998qiqi8239"]
["qiqi0998", "0998", index: 10, input: "qiqi123qiqi0998qiqi8239"]
["qiqi8239", "8239", index: 21, input: "qiqi123qiqi0998qiqi8239"]
["qiqi123", "qiqi0998", "qiqi8239"]
*/

var reg=/([a-z])([a-z])21/;
console.log(reg.test('abba'));

var reg=/([a-z])([0-9])(.)13/;
console.log(reg.exec('a0eae'));