Why doesn't it work?

// you need to 'assign' the array to the quiz variable with an = sign
// also you have an extra comma after the last array element
// var quiz [["2x1?", 2], ["2x2?", 4], ["2x3?", 6], ]; 
var quiz = [
  ["2x1?", 2],
  ["2x2?", 4],
  ["2x3?", 6]
];

var correctAnswer = 0,
    question,
    answer,
    response
    html;

function print(message) {
  document.write(message);
}

for (var i = 0; i < quiz.length; i += 1) {
  question = quiz[i][0];
  answer = quiz[i][1];
  response = parseInt(prompt(question));
  if (response === answer) {
    correctAnswer += 1;
  }
}

html = "You got " + correctAnswer + " question(s) right.";
print(html);