chapter5day1.js

/*eloquent javascript solution*/

var differences = ancestry.filter(function(person) {
  return byName[person.mother] != null;
}).map(function(person) {
  return person.born - byName[person.mother].born;
});

console.log(average(differences))

/* my solution */

var ageDifferences = [];

ancestry.forEach(function(person) {
  if (byName[person.mother] != null) {
    ageDifferences.push(person.born - byName[person.mother].born)
  }
})

console.log(average(ageDifferences))