Function escapePattern

escapePattern(pattern?: null | string): undefined | null | string
Returns a regex pattern that escaped the given pattern
Parameters
- Optionalpattern: null | string
  the pattern to inspect
Returns undefined | null | string
a regex pattern that escaped the given pattern
Author
David Hsing
Example
```
escapePattern('\\');    // '\\\\'
escapePattern('-+=');    // '\\-\\+='
```