Functions for validating and formatting commonly used swiss inputs

[fwermelinger]

names are suggestions

• isValidSwissSocialSecurityNumber(input: string) and formatSwissSocialSecurityNumber(input: string)
• isValidIbanNumber(input: string) and formatIBanNumber(input: string)

AHV
The formatting method should just check if it is 13 numbers and valid, if yes, return input 7561234567891 as 756.1234.5678.91

IBAN
The formatting method should be input: CH3900700115651849173 output CH39 0070 0115 6518 4917 3

We have this code in various projects for the AHV validation:

export const isAHVNumberValid = (socialInsuranceNumber: string): boolean => {
  // Validation of Social insurance number with regex and checking of checksum
  // Validation according to https://www.sozialversicherungsnummer.ch/aufbau-neu.htm
  const regex = new RegExp(/[7][5][6][.][\d]{4}[.][\d]{4}[.][\d]{2}$/);
  if (regex.test(socialInsuranceNumber)) {
    //todo check checksum
    const number = socialInsuranceNumber.substring(0, socialInsuranceNumber.length - 1);

    const reversedNumber = number.split(".").join("").split("").reverse().join("");

    let sum = 0;
    for (let i = 0; i < reversedNumber.length; i++) {
      sum += i % 2 == 0 ? Number(reversedNumber[i]) * 3 : Number(reversedNumber[i]) * 1;
    }

    const checksum = Math.ceil(sum / 10) * 10 - sum;
    const checknumber = parseInt(socialInsuranceNumber[socialInsuranceNumber.length - 1]);

    if (checksum !== checknumber) {
      return false;
    } else {
      return true;
    }
  } else {
    return false;
  }
};

[fwermelinger]

@drebrez can you check this request if it's a good addition? And also think about in what area this belongs? Strings, or should we put it in a new "swiss standards" area? I am thinking also IBAN numbers are useful and could go together.

[drebrez]

probably ok in the strings.ts file, at the end it's exported as single function from the package, they are not handled as namespaces.

for the checksum seems quite easy to check, something like this might work (found on internet)

var checkSum = ean.split('').reduce(function(p,v,i) {
    return i % 2 == 0 ? p + 1 * v : p + 3 * v;
}, 0);

edit: just noticed in your example there is already the checksum check, I didn't read the whole block and stopped at the "todo check checksum" 😅