Javascript Data Structure Hash Table in es5

function HashTable(size) {
  this.values = {};//from   w  w  w  .j a va2s  . co m
  this.numberOfValues = 0;
  this.size = size;
}

HashTable.prototype.add = function(key, value) {
  var hash = this.calculateHash(key);
  if(!this.values.hasOwnProperty(hash)) {
    this.values[hash] = {};
  }
  if(!this.values[hash].hasOwnProperty(key)) {
    this.numberOfValues++;
  }
  this.values[hash][key] = value;
};
HashTable.prototype.remove = function(key) {
  var hash = this.calculateHash(key);
  if(this.values.hasOwnProperty(hash) && this.values[hash].hasOwnProperty(key)) {
    delete this.values[hash][key];
    this.numberOfValues--;
  }
};
HashTable.prototype.calculateHash = function(key) {
  return key.toString().length % this.size;
};
HashTable.prototype.search = function(key) {
  var hash = this.calculateHash(key);
  if(this.values.hasOwnProperty(hash) && this.values[hash].hasOwnProperty(key)) {
    return this.values[hash][key];
  } else {
    return null;
  }
};
HashTable.prototype.length = function() {
  return this.numberOfValues;
};
HashTable.prototype.print = function() {
  var string = '';
  for(var value in this.values) {
    for(var key in this.values[value]) {
      string += this.values[value][key] + ' ';
    }
  }
  console.log(string.trim());
};

var hashTable = new HashTable(3);
hashTable.add('first', 1);
hashTable.add('second', 2);
hashTable.add('third', 3);
hashTable.add('fourth', 4);
hashTable.add('fifth', 5);
hashTable.print(); // => 2 4 1 3 5
console.log('length gives 5:', hashTable.length()); // => 5
console.log('search second gives 2:', hashTable.search('second')); // => 2
hashTable.remove('fourth');
hashTable.remove('first');
hashTable.print(); // => 2 3 5
console.log('length gives 3:', hashTable.length()); // => 3