Works but prints "undefined" too...

var student;
var name;
var track;
var achievements;
var points;
var html;

var students = [ 
  { 
    name: 'Bjorn Uchekov',
    track: 'Front End Development',
    achievements: 158,
    points: 14730
  },
  {
    name: 'Sammy Yamatori',
    track: 'iOS Development with Swift',
    achievements: 175,
    points: 16375
  },
  {
    name: 'Darth Fador',
    track: 'PHP Development',
    achievements: 55,
    points: 2025
  },
  {
    name: 'Don Chavez',
    track: 'Learn WordPress',
    achievements: '40',
    points: 1950
  },
  {
    name: 'Lil\' Kim Jung Uno',
    track: 'Rails Development',
    achievements: 5,
    points: 350
  }
];

var print = function(msg) {
  var box = document.getElementById('output');
  box.innerHTML = msg;
};

for(var i = 0; i < students.length; i += 1) {
  student = students[i];
  name = student.name;
  track = student.track;
  achievements = student.achievements;
  points = student.points;
  html += '<h2>' + name + '</h2>';
  html += '<p>Track: ' + track + '</p>';
  html += '<p>Achievements: ' + achievements + '</p>';
  html += '<p>Points: ' + points + '</p>';
}

print(html);