Useless regular-expression character escape

Using a regular expression with string literal (`new RegExp('[a-z]+')`) instead of regular expression slash syntax (`/[a-z]+/`) should be done with caution.
Usually, to escape `.` (dot) symbol within a regular expression, a developer would use backslash. But when it's done within a string literal (`new RegExp('\.')`) JavaScript will first process the string itself and only then call RegExp constructor.
It means `new RegExp('\.')` is equivalent to `/./`, which unintendedly allows to match any character instead of the intended dot only.
This may result in some security issues. For example, consider the hostname matching regular expression `new RegExp('www\.mysite\.com')`. In this case an input of `http://www-mysite.com/` will pass the validation.