使用 document.evaluate() 的 xpathResult 作为 contextNode 不起作用

Question

在使用document.evaluate时，我尝试再次使用xpathResult作为上下文节点，类似于附加的示例，但没有成功，我错在哪里？

const getAllLiButton = document.querySelector("#get-all-li");
const getTitleAndTextButton = document.querySelector("#get-title-text");
getAllLiButton.addEventListener("click", getAllLi);
getTitleAndTextButton.addEventListener("click", getTitleAndText);
function getAllLi() {
  var records = [];
  let topLevelResults = document.evaluate("/html/body/ul/li", document, null, XPathResult.ORDERED_NODE_ITERATOR_TYPE, null);
  var levelResult = topLevelResults.iterateNext();
  while (levelResult) {
    records.push(levelResult);
    
    levelResult = topLevelResults.iterateNext();
  }
  console.log(records);
}
function getTitleAndText() {
  let topLevelResults = document.evaluate("/html/body/ul/li", document, null, XPathResult.ORDERED_NODE_ITERATOR_TYPE, null);
  var levelResult = topLevelResults.iterateNext();
  let titleText = document.evaluate("/h3", levelResult, null, XPathResult.ORDERED_NODE_ITERATOR_TYPE, null);
  console.log(titleText);
  let textBox = document.evaluate("/span", levelResult, null, XPathResult.ORDERED_NODE_ITERATOR_TYPE, null);
  console.log(textBox);
}

<button id="get-all-li">Get all li (works)</button>
<button id="get-title-text">Get single Title & Text (not works)</button>
<ul>
  <li><h3>Title #1</h3><span>some text</span></li>
  <li><h3>Title #2</h3><span>some text</span></li>
  <li><h3>Title #3</h3><span>some text</span></li>
  <li><h3>Title #4</h3><span>some text</span></li>
  <li><h3>Title #5</h3><span>some text</span></li>
</ul>

提前感谢您的帮助！

Answer 1

如文档中报告的那样：

document.evaluate(".//h3", levelResult, null, XPathResult.ORDERED_NODE_ITERATOR_TYPE, null)

.//h3 xpathExpression 对于指示查询应从上下文节点 (levelResult( 开始非常重要。

const getAllLiButton = document.querySelector("#get-all-li");
const getTitleAndTextButton = document.querySelector("#get-title-text");
getAllLiButton.addEventListener("click", getAllLi);
getTitleAndTextButton.addEventListener("click", getTitleAndText);
function getAllLi() {
    var records = [];
    let topLevelResults = document.evaluate("/html/body/ul/li", document, null, XPathResult.ORDERED_NODE_ITERATOR_TYPE, null);
    var levelResult = topLevelResults.iterateNext();
    while (levelResult) {
        records.push(levelResult);
        levelResult = topLevelResults.iterateNext();
    }
    console.log(records);
}
function getTitleAndText() {
    let topLevelResults = document.evaluate("/html/body/ul/li", document, null, XPathResult.ORDERED_NODE_ITERATOR_TYPE, null);
    var levelResult = topLevelResults.iterateNext();
    let titleText = document.evaluate(".//h3", levelResult, null, XPathResult.ORDERED_NODE_ITERATOR_TYPE, null);
    titleText = titleText.iterateNext();
    console.log(titleText.textContent);
    let textBox = document.evaluate(".//span", levelResult, null, XPathResult.ORDERED_NODE_ITERATOR_TYPE, null);
    textBox = textBox.iterateNext();
    console.log(textBox.textContent);
}

<button id="get-all-li">Get all li (works)</button>
<button id="get-title-text">Get single Title & Text (not works)</button>
<ul>
    <li><h3>Title #1</h3><span>some text</span></li>
    <li><h3>Title #2</h3><span>some text</span></li>
    <li><h3>Title #3</h3><span>some text</span></li>
    <li><h3>Title #4</h3><span>some text</span></li>
    <li><h3>Title #5</h3><span>some text</span></li>
</ul>