s-valid/zipCode/index.ts

Simple validator for strings

// ----- zip code
//		--	1. input must be a string
//		--	2. check number
//		--	3. perform regex test
// ---------------------------------------
export default function(s: string) {

	// [1] throws here if not a string
	s = s.toLowerCase();

	// [2] every zip code begins with a number, and none are < 00501
	const numeric = parseInt(s, 10);

	if (isNaN(numeric) || numeric < 501) return false;

	// [3]
	const regex = /^\d{5}$/;
	return regex.test(s);
};