# `.` means "any single character" except newline

## `*` zero or more of the preceding match
## `+` one or more of the preceding match
## `[abc]` any one character of `a`, `b`, and `c`
## `(RX1|RX2)` either something that matches `RX1` or `RX2`
## `^` the start of the line
## `$` the end of the line
## 实用工具/参考资料

- <https://ihateregex.io/>
- <https://regex101.com/>
- <https://www.regular-expressions.info/>
- <https://emailregex.com/>


相关：[[js|js]]