javascript - 尝试读取 xml 文件时出现 AJAX 错误

Question

我正在尝试使用 ajax 从 xml 文件中检索一些数据

  <?xml version="1.0" encoding=UTF-8"?>

  <user>
     <u_idno>1</u_idno>
     <u_name>nobody</u_name>
     <u_srnm>nothing</u_srnm>
     <u_role>linux</u_role>
  </user>

  <user>
     <u_idno>2</u_idno>
     <u_name>yesbody</u_name>
     <u_srnm>something</u_srnm>
     <u_role>administrator</u_role>
  </user>

但我收到错误

Uncaught TypeError: Cannot read property 'getElementsByTagName' of null

我不确定为什么它会说 null，我一直在疯狂地搜索以找出我做错了什么，但我一无所知。我的javascript如下

  function f_ajax() {

     var lv_request;

     try {
        lv_request = new XMLHttpRequest();
     } catch (error) {
        lv_request = new ActiveXObject("Microsoft.XMLHTTP");
     }

     lv_request.onreadystatechange = function() {

        if(lv_request.readyState == 4 && lv_request.status == 200) {

           lv_xml = lv_request.responseXML;
           lv_row = lv_xml.getElementsByTagName("user");
           lv_output = null;

           for (lv_cnt = 0; lv_cnt < lv_row.length; lv_cnt++) {

              lv_output = lv_output + lv_row[lv_cnt].childNodes[0].nodeValue;

           }

           document.getElementById("h2_ajax").innerHTML = lv_row;

        }

     }

     lv_request.open("GET", "data.xml", true);
     lv_request.send();

  };

  f_ajax();

Answer 1

您的 XML 格式不正确。它缺少根并存在其他一些问题。试试这个:

<?xml version="1.0" encoding="UTF-8"?>
<root>
  <user>
   <u_idno>1</u_idno>
   <u_name>nobody</u_name>
   <u_srnm>nothing</u_srnm>
   <u_role>linux</u_role>
 </user>
 <user>
   <u_idno>2</u_idno>
   <u_name>yesbody</u_name>
   <u_srnm>something</u_srnm>
   <u_role>administrator</u_role>
 </user>
</root>