Node.js SHA-256 hash example

main.js

const fs = require('fs')
const crypto = require('crypto')


if (require.main === module) {
  main()
}

async function main () {
  try {
    const buffer = fs.readFileSync(process.argv[1])
    const digestSync = sha256hashSync(buffer)

    const stream = fs.createReadStream(process.argv[1])
    const digestAsync = await sha256hashAsync(stream)

    console.log({digestSync, digestAsync})
  } catch (err) {
    console.error(err)
  }
}

function sha256hashSync (buffer) { // <1>
  return crypto.createHash('sha256').update(buffer).digest('hex')
}

async function sha256hashAsync (stream) { // <2>
  return await new Promise((resolve, reject) => {
    const hash = crypto.createHash('sha256')

    hash.once('finish', () => resolve(hash.read().toString('hex')))
    stream.once('error', err => reject(err))

    stream.pipe(hash)
  })
}