https://www.w3.org/WAI/tutorials/forms/validation/
Validating Input | Web Accessibility Initiative (WAI) | W3C
Accessibility resources free online from the international standards organization: W3C Web Accessibility Initiative (WAI).
web accessibility initiativevalidating inputwaiw3c
https://www.perl.com/article/validating-untrusted-input-numbers/
Validating untrusted input: numbers
Common techniques and edge cases
inputnumbers