Question

我试图通过括号表示法访问其中一个对象属性，但我无法弄清楚它为什么不起作用。一如既往，非常感谢您的帮助！

JS：

    var dude = [
      {
        question1: "What is dude's favourite food?",
        choices1: ["Pizza", "Pasta", "Chips", "Ice cream"],
        answer1: 1

      },
      {
        question2: "What was dude's first ever job?",
        choices2: ["Staples", "Vodafone", "Costa", "Post office"],
        answer2: 0
      },

    ]

var counter = 1;

var currentQues = "question"+counter;

console.log(dude[currentQues]);

控制台返回“undefined”。这是因为它无法通过变量（currentQues）访问属性，该变量基本上包含另一个变量（计数器）？

与往常一样，非常感谢您的帮助。我只是一个希望前进的初学者。

Answer 1

dude指的是对象的数组。您正试图访问question1上的dude，但您需要在dude[0]上访问它：

console.log(dude[0][currentQues]);
// -------------^^^

直播示例：

＆＃13;

var dude = [
      {
        question1: "What is dude's favourite food?",
        choices1: ["Pizza", "Pasta", "Chips", "Ice cream"],
        answer1: 1

      },
      {
        question2: "What was dude's first ever job?",
        choices2: ["Staples", "Vodafone", "Costa", "Post office"],
        answer2: 0
      },

    ]

var counter = 1;

var currentQues = "question"+counter;

console.log(dude[0][currentQues]);

＆＃13;

我强烈建议您重新考虑该数据结构。所有对象的对象属性名称应该相同，只是它们在数组中的位置区分它们：

＆＃13;

var dude = [{
    question: "What is dude's favourite food?",
    choices: ["Pizza", "Pasta", "Chips", "Ice cream"],
    answer: 1
  },
  {
    question: "What was dude's first ever job?",
    choices: ["Staples", "Vodafone", "Costa", "Post office"],
    answer: 0
  },
]

dude.forEach(function(entry, index) {
  var num = index + 1;
  console.log("Question #" + num + ": " + entry.question);
});

＆＃13;

Answer 2

您还需要获取数组的索引。

var dude = [{ question1: "What is dude's favourite food?", choices1: ["Pizza", "Pasta", "Chips", "Ice cream"], answer1: 1 }, { question2: "What was dude's first ever job?", choices2: ["Staples", "Vodafone", "Costa", "Post office"], answer2: 0 }],
    counter = 1;
    currentQues = "question" + counter;

console.log(dude[counter - 1][currentQues]);
//               ^^^^^^^^^^^

无法通过括号变量表示法访问对象属性

2 个答案: