javascript - 即使存在 id，javascript id 选择器也会返回 null

Question

不知何故，在 js in const questionEl = document.getElementById('question');中返回 null。我检查了所有的 id 选择器，发现它们都返回 null。我无法理解问题的原因。我有具有指定 id 的元素。那为什么仍然返回null？

const questionEl = document.getElementById('question');
const a_text = document.getElementById("a");
console.log("This  is >>", a_text);
const b_text = document.getElementById("b");
const c_text = document.getElementById("c");
const d_text = document.getElementById("d");

let currentQuestion = 0;

function loadQuiz() {
  console.log(quizData[currentQuestion].question)
  questionEl.innerHTML = quizData[currentQuestion].question;
  currentQuestion++;
}

loadQuiz();

<div class="quiz-container">
  <div class="quiz-header">
    <h2 id="question">Question text</h2>
  </div>

  <ul class="quiz-options">
    <li>
      <input type="radio" id="a" name="answer">
      <label for="a" id="a_text">Question</label>
    </li>
    <li>
      <input type="radio" id="b" name="answer">
      <label for="a" id="b_text">Question</label>
    </li>
    <li>
      <input type="radio" id="c" name="answer">
      <label for="a" id="c_text">Question</label>
    </li>
    <li>
      <input type="radio" id="d" name="answer">
      <label for="a" id="d_text">Question</label>
    </li>
  </ul>
  <button>Next</button>
</div>

标签： javascripthtml