Javascript数组索引无法正常工作

Question

我目前正在尝试制作一个快速提示游戏，该游戏根据用户选择的类别和难度显示问题。 我正在尝试使用最少的代码使之最有效。

当前正在发生的事情是，我将类别保存在一个名为category的变量中，将难度值保存在一个称为难度的变量中。 当我尝试访问数组时，我使用category[difficulty].question因为我已经根据数组的类别对其进行了命名。

但是，它没有为适当的元素建立索引，而是尝试拼写类别的单词。 即，如果类别是地理位置并且难度很容易，我正在尝试使用category[difficulty].question访问geography[0].question category[difficulty].question 。 但是相反，我得到了单词geoography的第一个字母，因此控制台日志中显示的只是字符串字母g。

谁能解释为什么会这样，并提出解决方案。

ps我知道switch语句不再常用了，但这是一个分配，我必须使用它们。

//Set up variables

var difficulty;
var geography = [

  {
    question: 'What is the captial of Canada? ',
    answer: 'ottawa',
  },

  {
    question: 'Where are the oil sands located? ',
    answer: 'alberta',
  },

  {
    question: 'What is the capital of Nunavut?',
    answer: 'iqaluit',
  },

  {
    question: 'What is the capital of the Northwest Territories?',
    answer: 'yellowknife',
  },

];

var history = [

  {
    question: 'What year was Canada founded?',
    answer: '1867',
  },

  {
    question: 'What year did we engage in war against the United States?',
    answer: '1812',
  },

  {
    question: 'Difficult history question',
    answer: 'Difficult history answer',
  },

  {
    question: 'Fiendish history question',
    answer: 'Fiendish history answer',
  },

];

var artsAndCulture = [

  {
    question: 'Easy Arts and Culture Question',
    answer: 'Easy Arts and Culture Answer',
  },

  {
    question: 'Medium Arts and Culture Question',
    answer: 'Medium Arts and Culture Answer',
  },

  {
    question: 'Difficult Arts and Culture Question',
    answer: 'Difficult Arts and Culture Answer',
  },

  {
    question: 'Fiendish Arts and Culture Question',
    answer: 'Fiendish Arts and Culture Answer',
  },

];



//Sets up first user prompt and sets the value of category to the value the user entered

var category = prompt("Please select a category:\n\ngeography\nhistory\narts and culture\n");
switch (category) {
  case "geography":
    console.log('You have selected the geography category');
    console.log('The value of category is ' + category);
    break;
  case "history":
    console.log('You have selected the history category');
    console.log('The value of category is ' + category);
    break;
  case "artsAndCulture":
    console.log('You have selected the arts and culture category');
    console.log('The value of category is ' + category);
    break;
  default:
    console.log('default');
}


//Sets up second user prompt and sets the value of difficulty based on the user selection

var input2 = prompt("Please select a difficulty:\n\neasy\nmedium\ndifficult\nfiendish\n");
switch (input2) {
  case "easy":
    console.log('You have selected the easy difficulty');
    difficulty = 0;
    console.log('The value of difficulty is ' + difficulty);
    compareAnswer();
    break;
  case "medium":
    console.log('You have selected the medium difficulty');
    difficulty = 1;
    console.log('The value of difficulty is ' + difficulty);
    compareAnswer();
    break;
  case "difficult":
    console.log('You have selected the difficult difficulty');
    difficulty = 2;
    console.log('The value of difficulty is ' + difficulty);
    compareAnswer();
    break;
    case "fiendish":
    console.log('You have selected the fiendish difficulty');
    difficulty = 3;
    console.log('The value of difficulty is ' + difficulty);
    compareAnswer();
    break;
  default:
    console.log('default');
}


//compares user answer to actual answer
function compareAnswer() {

  var x = prompt(category[difficulty].question);
  console.log(category[difficulty]);
  console.log('You answered ' + x);
  console.log('The correct answer is ' + category[difficulty].answer);
  if (x == category[difficulty].answer) {
    console.log('You answered correctly!');
  } else {
    console.log('You answered incorrectly, the correct answer was ' + category[difficulty].answer);
  }
}

Answer 1

您为category分配了一个字符串值，但是将其用作数组引用。

假设您的JavaScript是在全局上下文中编写的：

var x = prompt(window[category][difficulty].question);

其他问题包括答案的大写/小写和\\narts and culture\\n");差异\\narts and culture\\n");不匹配的case "artsAndCulture":

Answer 2

我将类别数组放入一个对象中：

var selection={
  'geography': [{
    question: 'What is the captial of Canada? ',
    answer: 'ottawa'
  },{
    question: 'Where are the oil sands located? ',
    answer: 'alberta'
  },{
    question: 'What is the capital of Nunavut?',
    answer: 'iqaluit'
  },{
    question: 'What is the capital of the Northwest Territories?',
    answer: 'yellowknife'
  }],
'history':[{
    question: 'What year was Canada founded?',
    answer: '1867'
  },
  {
    question: 'What year did we engage in war against the United States?',
    answer: '1812'
  },{
    question: 'Difficult history question',
    answer: 'Difficult history answer'
  },{
    question: 'Fiendish history question',
    answer: 'Fiendish history answer'
  }],
'artsAndCulture': [{
    question: 'Easy Arts and Culture Question',
    answer: 'Easy Arts and Culture Answer'
  },{
    question: 'Medium Arts and Culture Question',
    answer: 'Medium Arts and Culture Answer'
  },{
    question: 'Difficult Arts and Culture Question',
    answer: 'Difficult Arts and Culture Answer'
  },{
    question: 'Fiendish Arts and Culture Question',
    answer: 'Fiendish Arts and Culture Answer'
}]};

然后向用户提问：

var x = prompt(selection[category][difficulty].question);

Answer 3

尝试将类别合并到一个对象中，例如var Categories = {geo：[]，history：[]}; 并从该对象中选择类别，以示例类别[category] ​​[difficulty]。 在您的示例类别中，只是从promt返回的字符串，未链接到数组或对象。