# Regex regular expression

## Function

Regex objects are created by regex(pattern, flags) and support test, match, replace and to_string. String prototype search, match, replace can also receive Regex parameters.

## API List

| API | Description |
| ------ | ------ |
| [Regex.test](/en/docs/regex/test) | Determine whether the text matches the current regular expression. |
| [Regex.match](/en/docs/regex/match) | Returns all matching fragments in the text. |
| [Regex.replace](/en/docs/regex/replace) | Replace text using the current regular expression. |
| [Regex.to_string](/en/docs/regex/to_string) | Returns the script text form of the regular expression. |

## Examples

```bt
rule = regex('BT', 'i')
result = rule.test('bt lang')

// Output: true
print result
```

## Notes

- Supported flags include i, m, s; the global replacement of replace additionally reads the g flag.