One of many ways!

var questions = [
  ['What is the best programming language?', 'javascript'],
  ['What keyword is used to declare a variable?', 'var'],
  ['What method is available to insert new items at the end of an array?', '.push()']
];
var correctGuesses = 0;
var correctQuestions = "<h2>You got these questions correct:</h2><ol>";
var incorrectQuestions = "<h2>You got these questions wrong:</h2><ol>";

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

function printCorrect(string) {
  string += "</ol>";
  print(string);
}

function printIncorrect(string) {
  string += "</ol>";
  print(string);
}

function quiz() {
  for ( var i = 0; i < questions.length; i++) {
    var response = prompt(questions[i][0]).toLowerCase();
    if (response === questions[i][1]) {
      correctGuesses += 1;
      correctQuestions += "<li>" + questions[i][0] + "</li>"
    } else {
      incorrectQuestions += "<li>" + questions[i][0] + "</li>"
    }
  }
  print('<p>You got ' + correctGuesses + ' right.</p>');
  printCorrect(correctQuestions);
  printIncorrect(incorrectQuestions);
}
quiz();