Implement the SDBM hash function in JavaScript

The SDBM algorithm is a simple hash function. It is a fast and simple function that can be used to hash strings into whole numbers. It is not suitable for cryptographic purposes, but it is great for creating unique identifiers for objects.

The algorithm itself is pretty straightforward. It iterates over each character in the input string, adding the character's Unicode value to the hash, and then left-shifting the hash by 6 and 16 bits, and finally subtracting the original hash value.

In order to implement it in JavaScript, you can use String.prototype.split() and Array.prototype.reduce() to create a hash of the input string, utilizing bit shifting as described above.

const sdbm = str => {
  let arr = str.split('');
  return arr.reduce(
    (hashCode, currentVal) =>
      (hashCode =
        currentVal.charCodeAt(0) +
        (hashCode << 6) +
        (hashCode << 16) -
        hashCode),
    0
  );
};

sdbm('name'); // -3521204949