Deep complex object fingerprinting/hashing in nodejs javascript (recursive).

hash-object.js

var crypto = require('crypto');

var ALGO = 'sha256';

function hashValue(val) {
  var hash = crypto.createHash(ALGO)
    , target;
  switch (toString.call(val)) {
    case '[object Object]':
      target = hashObject(val);
    break;
    case '[object Array]':
      target = hashArray(val);
    break;
    default:
      target = JSON.stringify(val);
    break;
  }
  // console.log('hashValue', val, target);
  return hash.update(target).digest('hex');
}

function hashObject(obj) {
  var hash = crypto.createHash(ALGO)
    , keys = Object.keys(obj || {});
  keys.sort(); // order of hash/dict is not guaranteed, so we do alpha
  for (var i=0; i < keys.length; i++) {
    var key = keys[i]
      , val = obj[key]
      , signature = hashValue(val);
    // console.log('signing - %s: %s => %s', key, val, signature);
    hash.update(key);
    hash.update(signature);
  }
  return hash.digest('hex');
}

function hashArray(arr) {
  var hash = crypto.createHash(ALGO);
  hash.setEncoding('hex');
  // FIXME: this probably needs some improvement.  i didn't want to just simply 
  // use arr.length, but if arr order changes the hash won't match
  arr.sort(); 
  for (var i=0; i < arr.length; i++) {
    var val = arr[i];
    hash.update(hashValue(val));
  }
  return hash.read();
}

module.exports = function(obj) {
  return hashValue(obj);
};