The BSN, PGN and OWN in the Netherlands can be validated with a 11 proef (elf proef). In this post I show you the JavaScript and TypeScript code.

In the Netherlands, we have a few identification numbers from the government. In this example, you can create a function to validate both of them based on the specification.

• BSN = Burgerservice nummer
• PGN = Burgerservice nummer in schools where the student doesn't have a BSN. The PGN is also called OWN.

How to use the code?

Define the function in your code and call it like this:

TypeScript example

// PGN/OWN
elfProefValidation('114435231', ElfproefType.own) // returns true;
elfProefValidation('34564366349', ElfproefType.own) // returns false;
// BSN
elfProefValidation('232262536', ElfproefType.bsn) // returns true;
elfProefValidation('247594057', ElfproefType.bsn) // returns false;

JavaScript example

// PGN/OWN
elfProefValidation('114435231', 'own'); // returns true;
elfProefValidation('34564366349', 'own')); // returns false;
// BSN
elfProefValidation('232262536', 'bsn')); // returns true;
elfProefValidation('247594057', 'bsn')); // returns false;

Try it on RunKit

Code

JavaScript function

function elfProefValidation(value, type) {
    let returnValue = false
    if (!value || value?.length === 0) {
        return true
    }
    if (value === '00000000000' || value.length !== 9) {
        return false
    }
    const values = value.split('')
    const firstCharacter = parseInt(values[0], 10)
    const lastCharacter = parseInt(values[values.length - 1], 10)
    const [a, b, c, d, e, f, g, h, i] = values.map(char => parseInt(char, 10))
    let result = 0

    if (type === 'bsn') {
        result = 9 * a + 8 * b + 7 * c + 6 * d + 5 * e + 4 * f + 3 * g + 2 * h + -1 * i
        returnValue = result > 0 && result % 11 === 0
    } else if (type === 'own') {
        result = 9 * a + 8 * b + 7 * c + 6 * d + 5 * e + 4 * f + 3 * g + 2 * h
        returnValue = result > 0 && firstCharacter === 1 && result % 11 === lastCharacter + 5
    } else {
        returnValue = false
    }

    return returnValue
}

TypeScript

export enum ElfproefType {
    bsn,
    own
}

function elfProefValidation(value: string, type: ElfproefType): boolean {
    let returnValue = false;
    if (!value || value?.length === 0) {
        return true;
    }
    if (value === '00000000000' || value.length !== 9) {
        return false;
    }
    const values = value.split('');
    const firstCharacter = parseInt(values[0], 10);
    const lastCharacter = parseInt(values[values.length - 1], 10);
    const [a, b, c, d, e, f, g, h, i] = values.map((char: string) => parseInt(char, 10));
    let result = 0;

    if (type === ElfproefType.bsn) {
        result = 9 * a + 8 * b + 7 * c + 6 * d + 5 * e + 4 * f + 3 * g + 2 * h + -1 * i;
        returnValue = result > 0 && result % 11 === 0;
    } else if (type === ElfproefType.own) {
        result = 9 * a + 8 * b + 7 * c + 6 * d + 5 * e + 4 * f + 3 * g + 2 * h;
        returnValue = result > 0 && firstCharacter === 1 && result % 11 === lastCharacter + 5;
    } else {
        returnValue = false;
    }

    return returnValue;
}

Thanks!

After reading this post, I hope you learned something new or are inspired to create something new! 🤗

If I left you with questions or something to say as a response, scroll down and type me a message. Please send me a DM on Twitter @DevByRayRay when you want to keep it private. My DM’s are always open 😁