How to declare mandatory regex block

[IgorStepanov]

Hello. I wrote the following code:

const maskOptions = {
	mask: "`RN-aaa",
	blocks: {
		RN: {
		  mask: /^\d+$/,
		}
	}
};
const mask = IMask(element, maskOptions);

I expect that "123-foo" will be accepted, but "-bar" will be rejected (because \d+ needs one or more digits).
However "-bar" is accepted.
Of cource, I use much complex regex than /^\d+$/, I reduced the example for clarity.