正则进阶

const str = 'some?content 123 abababcacb .md .txt  .js .ts'
const pattern  = /(\w+)\?(\w+)\s*.*(\.md)/;
str.match(pattern)//['some?content 123 abababcacb .md','some','content', '.md',];//第0索引表示整个正则匹配模式匹配到的字符，第1个索引开始就表示各个分组所匹配到的内容

const str = 'some?content 123 abababcacb .md .txt  .js .ts'
const pattern  = /(?<custom_name_1>\w+)\?(?<custom_name_2>\w+)\s*.*(\.md)/;
str.match(pattern)
console.log(RegExp.$1);//some

const str = 'some?content 123 abababcacb .md .txt  .js .ts'
const pattern  = /(?<custom_name_1>\w+)\?(?<custom_name_2>\w+)\s*.*(\.md)/;
str.match(pattern)
/**
[
  ...,
  groups:{
    custom_name_1: 'some',
    custom_name_2: 'content'
  }
]
* */

const str = 'some?content 123 abababcacb .md .txt  .js .ts'
const pattern  = /(?<custom_name_1>\w+)\?(?<custom_name_2>\w+)\s*.*(\.md)/;
const group = pattern.exec(str);// =>等于match的groups
const [custom_name_1,custom_name_2] = group;

const str = 'some?content 123 abababcacb .md .txt  .js .ts';
const pattern = /(?<custom_name_1>ab)\1\k<custom_name_1>/;//\1和\k<custom_name_1>,以前的 capture group 会用 \1, \2 来 back reference, 同理 named group 也一样可以, 语法是 \k<name>
console.log(pattern.exec(str)); // =>等于match的groups
//['ababab', 'ab',index: 17,input: 'some?content 123 abababcacb .md .txt  .js .ts', groups: [Object: null prototype] { custom_name_1: 'ab' }]

const str = 'some?content 123 abababcacb .md .txt  .js .ts'
const pattern  = /(?:\w+)\?(?:\w+)\s*.*(\.md)/;
str.match(pattern)//['some?content 123 abababcacb .md','.md', index: 0,input: 'some?content 123 abababcacb .md .txt  .js .ts',groups: undefined]

//匹配密码(必须有大写小写字母，以及数字，8位以上)
const str = 'asdASD123'
const pattern  = /^(?=.*[a-z])(?=.*[A-Z])(?=.*\d).{8,}$/;//匹配会站在某个位置去进行匹配，对于多个前瞻，都会站在同一个位置去匹配
pattern.test(str)
 
const str = 'asdASD123';
const pattern = /.*(?=ASD)/g; //匹配会站在某个位置去进行匹配，对于多个前瞻，都会站在同一个位置去匹配
 
console.log(str.match(pattern));//[ 'asd', '' ]

const strs = ['123abc', '12abcd', '123abcd', '13456abc', 'Aa2dadasdasdxabca'];
const pattern  = /^(?!123).*(?=abc$)/;//不以123开头并且以abc结尾
strs.forEach(str => {
	console.log(pattern.test(str));
});
 

//匹配以特定字符开头
const str = '2312asdASD123'
const pattern  = /(?<=asd).*/;
pattern.test(str)

// 匹配不是以123开头的abc
const regex = /(?<!123)abc/g;
console.log(regex.test("abc123")); // true
console.log(regex.test("123abc")); // false