XPathResult 的评估返回错误

Question

我有一个 xml，我想读取它的 <block> 节点。但是当我在 XPath 下执行时，它给我一个错误。

我正在尝试解析的xml：

   let x = `<xml>
    <block type="block_onGreenFlagClicked" id=";]jZ*Zs|[L-Sr{nhCB%V" x="25" y="0">
         <field name="NAME1">When</field>
         <statement name="function_name">
            <block type="helper_Player__walkSecondsDrop" id="9lo_/{gKTxB6/FRH2Pw">
             <field name="LABEL">Player.</field>
             <field name="DROP_Player__walkSecondsDrop$">walkForwardForNSeconds</field>
           </block>
       </statement>
    </block>
    </xml>`;



let doms = new DOMParser()
let v = doms.parseFromString(x, 'text/xml')
let r =  v.evaluate('/block',v, null, XPathResult.ANY_TYPE, null)

下面是结果说：

XPathResult {invalidIteratorState: false, resultType: 4, iterateNext: function, snapshotItem: function, ANY_TYPE: 0…}
  booleanValue: [Exception: TypeError: Failed to read the 'booleanValue' property from 'XPathResult': The result type is not a boolean.]
  invalidIteratorState: false
  numberValue: [Exception: TypeError: Failed to read the 'numberValue' property from 'XPathResult': The result type is not a number.]
  resultType: 4
  singleNodeValue: [Exception: TypeError: Failed to read the 'singleNodeValue' property from 'XPathResult': The result type is not a single node.]
  snapshotLength: [Exception: TypeError: Failed to read the 'snapshotLength' property from 'XPathResult': The result type is not a snapshot.]
  stringValue: [Exception: TypeError: Failed to read the 'stringValue' property from 'XPathResult': The result type is not a string.]
  __proto__: XPathResult

我不知道我做错了什么？任何人都可以指导我吗？

Answer 1

代码没有问题。 /block XPath 表达式什么都不选择，因为根元素是一个 xml 元素。将表达式更改为 //block 会选择这两个 block 元素。示例：

let x = `<xml>
    <block type="block_onGreenFlagClicked" id=";]jZ*Zs|[L-Sr{nhCB%V" x="25" y="0">
         <field name="NAME1">When</field>
         <statement name="function_name">
            <block type="helper_Player__walkSecondsDrop" id="9lo_/{gKTxB6/FRH2Pw">
             <field name="LABEL">Player.</field>
             <field name="DROP_Player__walkSecondsDrop$">walkForwardForNSeconds</field>
           </block>
       </statement>
    </block>
    </xml>`
let doms = new DOMParser()
let v = doms.parseFromString(x, 'text/xml')
let r = v.evaluate('//block', v, null, XPathResult.ANY_TYPE, null)

var s = new XMLSerializer();
var t = document.getElementById("output");
while ((n = r.iterateNext())) {
  t.value += (s.serializeToString(n)) + "\n";
}

<body>
  <textarea id="output" rows="15" cols="60"></textarea>
</body>

XPathResult 的评估返回错误

Evaluation of XPathResult is returning an error

javascript

xml

xpath

xmlhttprequest

xml-parsing