numericReg top-level property
A regular expression that matches integer numeric strings, including negatives.
This regex matches strings that consist of an optional leading minus sign (-)
followed by one or more digits (0-9). It does not allow decimal points,
whitespace, or any other characters.
Examples of valid matches:
123-456
Examples of invalid matches:
12.3+123abc
Implementation
RegExp numericReg = RegExp(numericRegStr);