cnpj.ts

// https://www.inf.ufpr.br/nicolui/grad/Programas/Curiosidades/Gerador-CPF/Algoritmo-CNPJ.txt
function validateDigit(cnpjValues: number[], extraDigit?: number) {
    const values = extraDigit != null ? [...cnpjValues, extraDigit] : cnpjValues
    let size = values.length
    let position = size - 7
    let sum = 0


    for (let i = 0; i < size; i++) {
        sum += values[i] * position--
        if (position < 2) {
            position = 9
        }
    }

    sum = sum % 11

    const calculatedDV = sum < 2 ? 0 : 11 - sum 

    return calculatedDV
}

const randomQuarter = () =>
    Math.trunc(Math.random() * 10000)
        .toString()
        .padStart(4, '0')

function generateCnpj(): string {
    const cnpj = randomQuarter() + randomQuarter() + '0001'
    const values = cnpj.split('').map(x => parseInt(x, 10))
    const firstDV = validateDigit(values)
    const secondDV = validateDigit(values, firstDV)

    return `${cnpj}${firstDV}${secondDV}`
}

const p = (raw: string) =>  {
  const rawValues = raw.split('').map(x => parseInt(x,10))
  
  let f = validateDigit(rawValues)
  console.log(f)
  console.log(validateDigit(rawValues,f))
}

// 18261995000100
p('182619950001')
p('523906180001')
for(let i = 0; i < 10; i++) {
  console.log(generateCnpj())
}