make_sha1_hashes.js

const crypto = require('crypto');
const stdin = process.openStdin();

const shasum = crypto.createHash('sha1');

console.log('Enter an email address to get the SHA1 hash as it would appear in a HIBP hashset file.');

stdin.addListener('data', data => {
  let trimmedString = data.toString().trim();
  console.log('You entered: [' + trimmedString + '], sha1 hash of lowercase: ');
  shasum.update(trimmedString.toLowerCase());
  console.log(shasum.digest('hex'));
  console.log('Enter an email address to get the SHA1 hash as it would appear in a HIBP hashset file.');
});