Function compilePattern

compilePattern(pattern?, flags?): RegExp | undefined
Returns a regex that compiled by the given pattern
Parameters
- Optionalpattern: string
  the pattern to inspect
- Optionalflags: string
  any combination of flag values
Returns RegExp | undefined
a regex that compiled by the given pattern
Example
```
compilePattern('[a-zA-Z0-9]+', 'g');
```