A numeric hash function that takes a string and outputs a number

hashStringAsNumber.js

function hashNumber(str) {
  let hash = 0;
  if (str.length === 0) return hash;
  for (let i = 0; i < str.length; i += 1) {
    const char = str.charCodeAt(i);
    hash = (hash << 5) - hash + char; // eslint-disable-line
    hash &= hash; // eslint-disable-line
  }
  return Math.abs(hash);
}

// hashNumber(str) % 10
// that will give you a constant way of getting a hash integer for the same string
// you can use, for instance, to hash a fingerprint string and then use this number
// to decide on some sort of variant for A/B tests or staged roll-outs