Question

简单的 JavaScript 测验数组问题

2016-05-27

433

javascript

我是编程新手，正在做 Treehouse 的测验。我不想只看答案，但我卡住了。我想将每个正确问题存储在一个新数组中，将每个错误问题也存储在一个新数组中，然后打印出来。我的代码会跟踪每个正确和错误的问题，但它只会将一个问题保存到每个新数组中，即使有多个问题是正确的或错误的。我确信这很简单，但我做错了什么？

var questions = [
  ['How many states are in the United States?', '50'],
  ['How many legs does a spider have?', '8'],
  ['How many continents are there?', '7']
];

function quiz(quizQuestions) {
  var counter = 0;
  
  for (var i = 0; i < questions.length; i++) {
    var answer = prompt(questions[i][0]);
    
    if (answer === questions[i][1]) {
      var correctAnswers = [questions[i][0]];
      counter += 1;
    } else {
      var wrongAnswers = [questions[i][0]];
    }
  }

  print('<h2>You got these questions right</h2>');
  print(correctAnswers);
  print('<h2>You got these questions wrong</h2>');
  print(wrongAnswers);
  
  var printQuestionsRight = '<h3>You got ' + counter + ' questions right</h3>';
  print(printQuestionsRight);
}

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

quiz(questions);

Answer 1

Use array to hold the questions than variable

join() 方法将数组的所有元素连接成一个字符串。

var questions = [
  ['How many states are in the United States?', '50'],
  ['How many legs does a spider have?', '8'],
  ['How many continents are there?', '7']
];
var correctAnswers = [];
var wrongAnswers = [];

function quiz(quizQuestions) {
  var counter = 0;
  for (var i = 0; i < questions.length; i++) {
    var answer = prompt(questions[i][0]);
    if (answer === questions[i][1]) {
      correctAnswers.push([questions[i][0]]);
      counter += 1;
    } else {
      wrongAnswers.push([questions[i][0]]);
    }
  }
  print('<h2>You got these questions right</h2>');
  print(correctAnswers.join('<br>'));
  print('<h2>You got these questions wrong</h2>');
  print(wrongAnswers.join('<br>'));
  var printQuestionsRight = '<h3>You got ' + counter + ' questions right</h3>';
  print(printQuestionsRight);
}

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

Fiddle 演示

Answer 2

首先，不要为正确和错误答案重新声明变量。每次回答问题时，将问题推送到变量上：

var questions = [
  ['How many states are in the United States?', '50'],
      ['How many legs does a spider have?', '8'],
      ['How many continents are there?', '7']
    ],
    correctAnswers = [],
    wrongAnswers = [];

    function quiz(quizQuestions) {
      var counter = 0;
      
      for (var i = 0; i < questions.length; i++) {
        var answer = prompt(questions[i][0]);
        
        if (answer === questions[i][1]) {
          correctAnswers.push ([questions[i][0]]);
          counter += 1;
        } else {
          wrongAnswers.push ([questions[i][0]]);
        }
      }

      print('<h2>You got these questions right</h2>');
      print(correctAnswers);
      print('<h2>You got these questions wrong</h2>');
      print(wrongAnswers);
      
      var printQuestionsRight = '<h3>You got ' + counter + ' questions right</h3>';
      print(printQuestionsRight);
    }

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

    quiz(questions);