safer-hash.js

var seed = Math.random() + '';

/**
 * Call this early in your program and only once and only if you are
 * paranoid about the amount of entropy in Math.random().
 */
exports.srand = function(newSeed) {
  seed = newSeed + '';
}

exports.create = function() {
  return new SaferHash();
}

function SaferHash() {
  var storage = {};

  this.g = this.get = function(key) {
    key = seed + key;
    return storage[key];
  };

  this.s = this.set = function(key, val) {
    key = seed + key;
    storage[key] = val;
    return this;
  };

  this.contains = function(key) {
    key = seed + key;
    return key in storage;
  };

  this.keys = function() {
    return Object.keys(storage).map(function(key) {
      return key.substring(seed.length);
    });
  };

  this.delete = function(key) {
    key = seed + key;
    return delete storage[key];
  }

  this.toJSON = function() {
    var self = this;
    return this.keys().map(function(key) {
      var val = self.get(key);
      return [key, val];
    });
  }

  this.toUnsafeObject = function() {
    var self = this;
    var obj = {};
    this.keys().forEach(function(key) {
      var val = self.get(key);
      obj[key] = val;
    });
    return obj;
  }
}

// Tests
(function() {

var saferHash = exports;

var hash = saferHash.create();

is('val', hash.set('key', 'val').get('key'));
is('val', hash.s('key', 'val').g('key'));
ok(hash.contains('key'));
ok(!hash.contains('DoesNotContain'));

is(1, hash.keys().length);
is('key', hash.keys()[0]);

is(JSON.stringify([['key', 'val']]), JSON.stringify(hash));

var unsafe = hash.toUnsafeObject();
is(JSON.stringify({'key': 'val'}), JSON.stringify(unsafe));

hash.delete('key');
is(0, hash.keys().length);

hash.s('foo', 'bar').s('key', 'val');
ok(hash.contains('foo'));
ok(hash.contains('key'));
ok(!hash.contains('bar'));
is(2, hash.keys().length);

var keys = hash.keys();

if (keys[0] == 'foo') {
  is(keys[1], 'key');
}
else if (keys[0] == 'key') {
  is(keys[1], 'foo');
} else {
  ok(false);
}

})();

// Test functions

function ok(val) {
  if (val) {
    console.log("OK");
  } else {
    console.log("NOT OK")
  }
}

function is(expected, result) {
  ok(expected === result);
}