RSA Cryptosystem Math

I wanted to learn more about the RSA Cryptosystem so I started reading more about the math behind it. So far I've been able to generate the following example in JavaScript. This uses pre-calculated values however the comments describe the rule behind arriving at the values.

var rsa_cryptosystem = {
  //1. Select two distinct prime numbers p and q
  p: 3,
  q: 11,
  //2. compute n as a product of pq
  n: rsa_cryptosystem.p*rsa_cryptosystem.q,
  //3. choose a variable z such that it is a co-prime to n
  z: (rsa_cryptosystem.p-1)*(rsa_cryptosystem.q-1),
  //4. choose variable pubK such that 1 < pubK < z and pubK is prime and co-prime to n
  pubK: 7,
  //5. choose privK such that (privK*e)%z = 1 and privK is prime
  privK: 3,
  encrypt: function(m) {
    return Math.pow(m, rsa_cryptosystem.pubK)%rsa_cryptosystem.n;
  },
  decrypt: function(m) {
    return Math.pow(m, rsa_cryptosystem.privK)%rsa_cryptosystem.n;
  }
}

Observation

It appears the values that can be encrypted within this system are limited to the value used to calculate the modulus, in this case 33.

for(var i = 0; i < 1000; i++) {
  var m = rsa_cryptosystem.encrypt(i);
  if (i == rsa_cryptosystem.decrypt(m)) {
    console.log('True %s', i);
  } else {
    console.log('False %s', i);
  }
}