Sequence generator (Javascript exercise)

Sequence generator

var naturals = new NaturalGen();
var evens = new EvenGen();
var odds = new OddGen();
var fibbs = new FibbGen();
var matches = new Match(evens, fibbs);

for (var i = 0; i < 10; i++) {
  console.log(naturals.next());
  console.log(evens.next());
  console.log(odds.next());
  console.log(fibbs.next());
  console.log(matches.next());
}

// Should return: 1 2 3 4 5
function NaturalGen() {
  var n = 1;
  this.next = function() {
    return n++;
  }
}

// 2 4 6 8 ... 20
function EvenGen() {
  var n = 1;
  this.next = function() {
    return ;
  }
}

// 1 3 5 7 ... 19
function OddGen() {
  this.next = function() {
    return ;
  }
}

function FibbGen() {
  var n = 0;
  var m = 1;
  this.next = function() {
    var p = ;
    return ;
  }
}

// Return similar numbers from 2 sequels
function Match(seqA, seqB) {
  this.next = function() {
    var a = seqA.next();
    var b = seqB.next();
    while (a != b) {
    }
    return a;
  }
}