Validar CNPJ em js

cnpj.js

validateCNPJ = cnpj => {

    function getDV(value) {
        let regDigits = (value.split('')).reverse()

        let mod1 = getModule(regDigits)
        let mod2 = getModule([mod1,...regDigits])

        return `${mod1}${mod2}`
    }

    function getModule(value) {
        let weights = [6, 5, 4, 3, 2, 9, 8, 7, 6, 5, 4, 3, 2]
        let reversed = weights.reverse()
        let sum = sumValues(value, reversed)
        let mod = sum % 11
        return mod < 2 ? 0 : 11 - mod
    }

    function sumValues(values, weights) {
        let sum = 0
        for (let i = 0; i < values.length; i++) {
            const element = values[i];
            sum += element * weights[i]
        }

        return sum
    }

    cnpj = ('' + cnpj).replace(/\D/g, '')
    if (cnpj.length != 14) return false

    let verificationDigit = cnpj.slice(12, 14)
    let registration = cnpj.slice(0, 12)

    let dv = getDV(registration)

    return dv == verificationDigit
}