a.js

function A() {
  this.type = 'a'
}

module.exports = A;
var B = require('./b.js');

A.prototype.delete = function deleteA(callback) {
  var self = this;
  
  self.findAllBs(function(err, res) {
    res.forEach(function(b) {
      var b = new B(b);
      b.delete();
    });
  });
}

b.js

function B() {
  this.type = 'b'
}

module.exports = B;
var A = require('./a.js');

B.prototype.read = function readB(callback) {
  var self = this;
  
  var myA = new A(self.a)
  myA.read(function(err, res) {
    return callback(null, 'My A:'+ res);
  })
}