Convert GUID (UUID) to integer numbers in Javascript (and back again)

explanation.js

// A UUID is a 128-bit number which is too large to be represented as a native integer in Javascript.
// The original solution I posted (based on https://github.com/uuidjs/uuid#uuidparsestr ) wasn't good,
// as it converted the given UUID into a byte array and then selected only the first four bytes to be
// used as the integer.

const uuid = require('uuid');

let convertGuidToInt = (uuid) => {
    // parse accountId into Uint8Array[16] variable
    let parsedUuid = uuid.parse(uuid);
    console.log(`uuid ${uuid} parsed successfully`);

    // convert to integer - see answers to https://stackoverflow.com/q/39346517/2860309
    let buffer = Buffer.from(parsedUuid);
    console.log(`parsed uuid converted to buffer`);
    let result = buffer.readUInt32BE(0);
    console.log(`buffer converted to integer ${result} successfully`);

    return result;
},

// The above example drops most of the number and so is a) impossible to convert back to UUID
// and b) unlikely to ensure uniqueness. In response to the requests for a way to convert the
// resulting integers back to UUIDs, here is the code to convert UUIDs to BigNumber objects
// and back again using the bignumber.js package:

const BigNumber = require('bignumber.js');

let convertGuidToInt = (id) => {
    // remove the dashes from the given uuid and convert to a hexadecimal BigNumber object
    const bn = new BigNumber(id.replace(/-/g, ''), 16);
    // return the string representation of the BigNumber object as a decimal
    return bn.toString(10);
};

let convertIntToGuid = (num) => {
    // convert the string representation of the decimal number to a BigNumber object
    const bn = new BigNumber(num, 10);
    // convert the BigNumber to a hexadecimal string
    const id = bn.toString(16);
    // return the string with the dashes (8-4-4-4-12)
    return `${id.substr(0, 8)}-${id.substr(8, 4)}-${id.substr(12, 4)}-${id.substr(16, 4)}-${id.substr(20)}`;
};

uuidToInt.js

const BigNumber = require('bignumber.js');

let convertGuidToInt = (id) => {
    // remove the dashes from the given uuid and convert to a hexadecimal BigNumber object
    const bn = new BigNumber(id.replace(/-/g, ''), 16);
    // return the decimal representation of the BigNumber object as a string
    return bn.toString(10);
};

let convertIntToGuid = (num) => {
    // convert the string representation of the decimal number to a BigNumber object
    const bn = new BigNumber(num, 10);
    // convert the BigNumber to a hexadecimal string
    const id = bn.toString(16);
    // return the string with the dashes (8-4-4-4-12)
    return `${id.substr(0, 8)}-${id.substr(8, 4)}-${id.substr(12, 4)}-${id.substr(16, 4)}-${id.substr(20)}`;
};