1. 点符号表示匹配除了换行符外的任意字符

   let pattern = /g..gle/;             
   let str = 'g12gle';
   alert(pattern.test(str));
   

2. o*，表示0个，1个，或者多个o

    let pattern = /go*gle/;             
    let str = 'gbbbgle';
    alert(pattern.test(str));
   

3. o+，表示1个，或者多个

    let pattern = /go+gle/;             
    let str = 'ggle';
    alert(pattern.test(str));
   

4. o?，表示1个，或者0个

    let pattern = /go?gle/;             
    let str = 'google';
    alert(pattern.test(str));
    
   

5. .?，表示1个，或者0个的任意字符

    let pattern = /g.?gle/;             
    let str = 'gbbgle';
    alert(pattern.test(str));
   

6. o{2,4}表示匹配o2-4次，包含2和4

    let pattern = /go{2,4}gle/;         
    let str = 'google';
    alert(pattern.test(str));
   

7. o{3}，表示只能限定为3个

    let pattern = /go{3}gle/;               
    let str = 'goooogle';
    alert(pattern.test(str));
   

8. o{3,}，表示为3个或3个以上

    let pattern = /go{3,}gle/;          
    let str = 'goooooooooooooooooooogle';
    alert(pattern.test(str));
   

9. [a-z]表示26个小写字母，任意一个都可以匹配

    let pattern = /[a-z]oogle/;         
    let str = '6oogle';
    alert(pattern.test(str));
   

10. [A-Z]表示26个大写字母，任意一个都可以匹配

 let pattern = /[A-Z]oogle/;         
 let str = 'Google';
 alert(pattern.test(str));

11. [0-9]*，表示0次，一次，或者多次

 let pattern = /[0-9]*oogle/;            
 let str = '44444oogle';
 alert(pattern.test(str));

12. [a-zA-Z0-9]表示匹配大小写的a-zA-Z0-9

 let pattern = /[a-zA-Z0-9]oogle/;   
 let str = 'oogle';
 alert(pattern.test(str));

13. [^0-9]表示非0-9的任意字符

 let pattern = /[^a-zA-Z0-9]oogle/;  
 let str = '_oogle';
 alert(pattern.test(str));

14. 这个^符号，是加在/后面的而不是[]里面的

 let pattern = /^[0-9]oogle/;            
 let str = '444oogle';
 alert(pattern.test(str));

15. +号，可以匹配一个或者多个

 let pattern = /^[0-9]+oogle/;           
 let str = '444oogle';
 alert(pattern.test(str));

16. \w表示[a-zA-Z_]

 let pattern = /\woogle/;                
 let str = '-oogle';
 alert(pattern.test(str));

17. \W表示[^a-zA-Z_]

 let pattern = /\Woogle/;                
 let str = '-oogle';
 alert(pattern.test(str));

18. \d表示[0-9]

 let pattern = /\doogle/;                
 let str = 'aoogle';
 alert(pattern.test(str));

19. \D表示[^0-9]

 let pattern = /\Doogle/;                
 let str = '1oogle';
 alert(pattern.test(str));

20. ^强制首匹配，$强制尾匹配

 let pattern = /^[a-z]oogl[0-9]$/;   
 let str = 'googl5';
 alert(pattern.test(str));

 ```
 
21. \S匹配非空白字符,\s匹配空白字符、空格、制表符和换行符
 
 ``` 
 let pattern = /\S\.vue$/;               
 let str = 'index.vue';
 alert(pattern.test(str));