正则表达式

1.判断是不是URL

let s1 = /(((^https?:(?:\/\/)?)(?:[-;:&=\+\$,\w]+@)?[A-Za-z0-9.-]+|(?:www.|[-;:&=\+\$,\w]+@)[A-Za-z0-9.-]+)((?:\/[\+~%\/.\w-_]*)?\??(?:[-\+=&;%@.\w_]*)#?(?:[\w]*))?)$/g;

2.判断是不是以英文和下划线组成

let regex = /^[a-zA_Z]*_*$/;

3.判断是不是以&#开头 ；结束

let regex = /^&#.*;$/;

4.防注入sql

.*( and |exec |insert |select |delete |update | count |%| chr | mid | master | truncate |char |declare | or |show |drop ).*