Question

我的代码中一直出现此错误。

Uncaught TypeError: Cannot set property 'innerHTML' of undefined我已阅读其他一些类似错误Uncaught TypeError: Cannot set property 'innerHTML' of undefined of null的帖子，我尝试了一些建议的方法，但似乎没有任何改变。

似乎指向这一行document.getElementsByClassName("demo")[i].innerHTML = xhttp.responseText;我不知道为什么像之前我添加循环一样，它运行良好。

我的代码

<%@LANGUAGE="VBSCRIPT" CODEPAGE="65001"%>
<!--#include file="../Connections/DVerto.asp" -->
<%
Dim Recordset1
Dim Recordset1_cmd
Dim Recordset1_numRows

Set Recordset1_cmd = Server.CreateObject ("ADODB.Command")
Recordset1_cmd.ActiveConnection = MM_DVerto_STRING
Recordset1_cmd.CommandText = "SELECT Part_Number FROM dbo.Stock_Header WHERE Part_Number like '84%'" 
Recordset1_cmd.Prepared = true

Set Recordset1 = Recordset1_cmd.Execute
Recordset1_numRows = 0
%>
<%
Dim Repeat1__numRows
Dim Repeat1__index

Repeat1__numRows = 10
Repeat1__index = 0
Recordset1_numRows = Recordset1_numRows + Repeat1__numRows
%>
<!doctype html>
<html>
<head>
<meta charset="utf-8">
<title>Untitled Document</title>
</head>

<body onLoad="loadDoc()">
<table width="50%" border="0" cellspacing="2" cellpadding="2">
  <% 
While ((Repeat1__numRows <> 0) AND (NOT Recordset1.EOF)) 
%>
  <tr>
    <td class="prodref"><%=(Recordset1.Fields.Item("Part_Number").Value)%></td>
    <td class="demo">&nbsp;</td>
  </tr>
  <% 
  Repeat1__index=Repeat1__index+1
  Repeat1__numRows=Repeat1__numRows-1
  Recordset1.MoveNext()
Wend
%>
</table>
<script>
var a = document.getElementsByClassName("prodref").length;
var i = 0;
for (i; i < a; i++) {
    loadDoc();
}
function loadDoc() {
    var a = document.getElementsByClassName("prodref");
    a[i] = document.getElementsByClassName("prodref").innerHTML;
  var xhttp = new XMLHttpRequest();
  xhttp.onreadystatechange = function() {
    if (xhttp.readyState == 4 && xhttp.status == 200) {
      document.getElementsByClassName("demo")[i].innerHTML = xhttp.responseText;
    }
  };
  xhttp.open("GET", "data.asp?prodref="+a[i].innerHTML, true);
  xhttp.send();
}
</script>

</body>
</html>
<%
Recordset1.Close()
Set Recordset1 = Nothing
%>

Answer 1

您正在进行异步请求，因此当调用 onreadystatechange 函数时，变量 i 将不是您所期望的。

试试这个：

...
for (i; i < a; i++) {
    loadDoc(i);
}

function loadDoc(i) {
...

Answer 2

您需要将i传递给函数，因为在AJAX请求返回时循环已完成。

var prodref = document.getElementsByClassName("prodref");
var demo = document.getElementsByClassName("demo");
var i = 0;
var a = prodref.length;

for (i; i < a; i++) {
    loadDoc(i);
}

function loadDoc(i) {
  console.log("creating loadDoc() call for", i);

  var xhttp = new XMLHttpRequest();

  xhttp.onreadystatechange = function() {
    console.log("callback invoked for", i, "with state:", xhttp.readyState);

    if (xhttp.readyState == 4 && xhttp.status == 200) {
      console.log("setting .innerHTML for", i, "to:", xhttp.responseText);
      demo[i].innerHTML = xhttp.responseText;
    }
  };

  xhttp.open("GET", "data.asp?prodref="+prodref[i].innerHTML, true);
  xhttp.send();
}

现在i的每个单独调用都有一个loadDoc变量，并且您在该函数中创建的回调函数将关闭该本地i。

这是一个闭包。

我也缓存了您的DOM选择。除非您认为它们会发生变化，否则您无需反复提取节点。

错误 - 未捕获的TypeError：无法设置未定义的属性“innerHTML”

2 个答案: