無法通過括號變量表示法訪問對象屬性

Question

我試圖通過方括號表示法訪問對象屬性之一，但是我無法弄清為什么它不起作用。 一如既往，非常感謝您的幫助！

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“未定義”。 這是因為它無法通過本質上包含另一個變量（計數器）的變量（currentQues）訪問屬性嗎？

與往常一樣，我們非常感謝您的幫助。 我只是想進步的初學者。

Answer 1

dude是指對象數組 。 您正在嘗試在dude上訪問question1 ，但是您需要在dude[0]上訪問它：

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

現場示例：

 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]); 

---

我強烈建議您重新考慮該數據結構。 所有對象的對象屬性名稱都應該相同，只是它們在數組中的位置可以區分它們：

 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); }); 

Answer 2

您還需要獲取數組的索引。

 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]); // ^^^^^^^^^^^