如何将一些XML值赋给JavaScript变量？

// 1. 发送HTTP请求并获取XML数据
var xhr = new XMLHttpRequest();
xhr.open('GET', 'example.xml', true);
xhr.onreadystatechange = function() {
  if (xhr.readyState === 4 && xhr.status === 200) {
    // 2. 解析XML数据为DOM对象
    var parser = new DOMParser();
    var xmlDoc = parser.parseFromString(xhr.responseText, 'text/xml');

    // 3. 提取XML值
    var title = xmlDoc.getElementsByTagName('title')[0].textContent;
    var author = xmlDoc.getElementsByTagName('author')[0].textContent;

    // 4. 将XML值赋给JavaScript变量
    var book = {
      title: title,
      author: author
    };

    console.log(book); // 输出：{ title: 'Book Title', author: 'Author Name' }
  }
};
xhr.send();

<book>
  <title>Book Title</title>
  <author>Author Name</author>
</book>