validera personnummer

socialSecurityCheck.ts

function validate(personnummer: string): boolean {
    let isValid = false
    const pnrRegex = new RegExp(/^(\d{6}|\d{8})(-?)(\d{4})/, 's')
    const parts = pnrRegex.exec(personnummer)
    personnummer = parts?.[1] || '' + parts?.[3] || ''

    if (personnummer.length === 12) {
        personnummer = personnummer.substring(2)
    }

    if (personnummer.length === 10) {
        let sum = 0
        const digits = personnummer.split('').map(Number)

        for (let i = 0; i < digits.length; i++) {
            if (i % 2 === 0) {
                let double = digits[i] * 2
                if (double > 9) {
                    double -= 9
                }
                sum += double
            } else {
                sum += digits[i]
            }
        }

        if (sum % 10 === 0) {
            isValid = true
        }
    }

    return isValid
}