gistfile1.js

var people = [
  {
    firstName: 'Phil',
    lastname: 'Gambling',
    age: 31
  },
  {
    firstName: 'Chris',
    lastName: 'Pounds',
    age: 26
  }
];

people.sort(function(a, b) {
  return a.age - b.age;
});

people.sort(function(a, b) {
  return (a.firstName + ' ' + a.lastName) - (b.firstName + ' ' + b.lastName);
});