A validator for Brazilian CPF and CNPJ documents

DocumentValidator.js

// This validator does not check the formatting of the documents.
// Documents can be passed with or without formatting characters.

const processes = {
	cpf: {
		length: 11,
		validator: [11, 10, 9, 8, 7, 6, 5, 4, 3, 2],
		validationRegex: (d1, d2) => `([0-9]{9}${d1}${d2})`,
		format: [/(\d{3})(\d{3})(\d{3})(\d{2})/, "$1.$2.$3-$4"],
	},
	cnpj: {
		length: 14,
		validator: [6, 5, 4, 3, 2, 9, 8, 7, 6, 5, 4, 3, 2],
		validationRegex: (d1, d2) => `([0-9]{12}${d1}${d2})`,
		format: [/(\d{2})(\d{3})(\d{3})(\d{4})(\d{2})/, "$1.$2.$3/$4-$5"],
	},
}

const convertCheckNumber = (checkNumber) => {
	const convertedDigit = (checkNumber * 10) % 11;
	return convertedDigit > 9 ? 0 : convertedDigit;
}

export function validateDocument({ document = "", type = "" }) {
	// Strip all non-numeric characters
	const sanitizedDocument = document.replace(/[^\d]+/g, '');

	if (!processes[type]) {
		const typesLength = Object.keys(processes).map(process => processes[process].length);
		const maxLength = typesLength.find(length => sanitizedDocument.length <= length);

		if (!maxLength) {
			return {
				isValid: false,
				type: "none",
				value: sanitizedDocument,
				formattedValue: sanitizedDocument,
			};
		}

		type = Object.keys(processes).find(process => processes[process].length === maxLength);
	}

	// Retrieve unique process values based on type
	const { validator, validationRegex, length, format } = processes[type];

	// CPF and CNPJ cannot be a sequence of equal numbers, e.g. 111.111.111-11 and 11.111.111/1111-11
	const isInvalidDocument = /^(\d)\1+$/.test(sanitizedDocument);

	if (isInvalidDocument || sanitizedDocument.length !== length) {
		return {
			isValid: false,
			type,
			value: sanitizedDocument,
			formattedValue: sanitizedDocument,
		};
	}

	const [firstCheckNumber, secondCheckNumber] = validator.reduce(([firstCN, secondCN], value, index) => [
		firstCN + (sanitizedDocument[index - 1] || 0) * value,
		secondCN + sanitizedDocument[index] * value,
	], [0, 0]);

	const firstDigit = convertCheckNumber(firstCheckNumber);
	const secondDigit = convertCheckNumber(secondCheckNumber);

	const checkLastDigits = new RegExp(validationRegex(firstDigit, secondDigit));

	return {
		isValid: checkLastDigits.test(sanitizedDocument),
		type,
		value: sanitizedDocument,
		formattedValue: sanitizedDocument.replace(...format),
	};
}