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HarmonyOS
我在学习javascript用xpath解析html文档。
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title></title>
</head>
<body>
<ul>
<li>th1 node</li>
<li>th2 node</li>
<li>th3 node</li>
<li>th4 node</li>
<li>th5 node</li>
</ul>
<script charset="utf-8" type="text/javascript" >
var documentNode=document.body;
const iterator1 = document.evaluate('//li', documentNode, null, XPathResult.UNORDERED_NODE_ITERATOR_TYPE, null);
try {
let thisNode = iterator1.iterateNext();
while (thisNode) {
console.log(thisNode.textContent);
thisNode = iterator1.iterateNext();
}
}
catch(e) {
console.log(`Error: Document tree modified during iteration ${e}`);
}
const iterator2 = document.evaluate('//p', documentNode, null, XPathResult.UNORDERED_NODE_ITERATOR_TYPE, null);
try {
let thisNode = iterator2.iterateNext();
while (thisNode) {
console.log(thisNode.textContent);
thisNode = iterator2.iterateNext();
}
}
catch(e) {
console.log(`Error: Document tree modified during iteration ${e}`);
}
</script>
</body>
</html>上面的html文件，
const iterator1 = document.evaluate('//li', documentNode, null, XPathResult.UNORDERED_NODE_ITERATOR_TYPE, null);可以得到正确的结果，这个很正常。
现在换用
const iterator2 = document.evaluate('//p', documentNode, null, XPathResult.UNORDERED_NODE_ITERATOR_TYPE, null);节点p根本就不存在文档中，
try {
let thisNode = iterator2.iterateNext();
while (thisNode) {
console.log(thisNode.textContent);
thisNode = iterator2.iterateNext();
}
}
catch(e) {
console.log(`Error: Document tree modified during iteration ${e}`);这里的try catch中的console.log 没有error信息输出。
Error: Document tree modified during iteration
请问，原因在哪里？
没有找到p，应该是返回了Null，不满足循环，while里面的Null.属性也不会执行就不抱错呗