我使用multiview选项创建了两个视图。现在在运行时，我收到了这个错误：
Microsoft JScript runtime error: 'null' is null or not an object
代表此代码：
window.onload = function checkbox(check) {
var check = document.getElementById("<%=cbxAuth.ClientID %>"); //<- error from here
check.onchange = function checkbox(check) {
if (this.checked == true)
{
document.getElementById("<%=txtUsName.ClientID %>").disabled = false;
document.getElementById("<%=txtPassword.ClientID %>").disabled = false;
}
else
{
document.getElementById("<%=txtUsName.ClientID %>").disabled = true;
document.getElementById("<%=txtPassword.ClientID %>").disabled = true;
}
}; // Till here
};
现在，当我在动态分析代码时，我意识到这是在我的第二个视图中，整个代码不存在于动态运行时。
这是我创建视图的前端代码：
<td>
<asp:Button Text="Generate License" BorderStyle="None" ID="Tab1" CssClass="Initial"
runat="server" OnClick="Tab1_Click" ValidationGroup="generatelicence" />
<asp:Button Text="Mail Configuration" BorderStyle="None" ID="Tab2" CssClass="Initial"
runat="server" OnClick="Tab2_Click" ValidationGroup="sendemail" />
<asp:MultiView ID="MainView" runat="server">
这是我创建第二个视图时的代码：
<asp:View ID="View2" runat="server">
<table style="width: 100%; border-width: 1px; border-color: #666; border-style: solid">
<tr>
<td class="style15">
FROM
</td>
<td>
<asp:TextBox ID="txtFrom" runat="server" Width="414px" CssClass="Textbox1"></asp:TextBox>
<asp:LinkButton ID="lbEdit0" runat="server" onclick="lbEdit0_Click"> Edit </asp:LinkButton>
<asp:RegularExpressionValidator ID="regexSendFrom" runat="server" ControlToValidate="txtFrom"
ErrorMessage="Enter a Valid Name" ValidationExpression="\w+([\s-_]\w+)*" ValidationGroup="sendemail"></asp:RegularExpressionValidator>
</td>
</tr>
<tr>
<td class="style15">
SENDER MAIL</td>
<td>
<asp:TextBox ID="txtMailAdd" runat="server" Width="414px" CssClass="Textbox1"></asp:TextBox>
<asp:LinkButton ID="lbEdit1" runat="server" onclick="lbEdit1_Click"> Edit
</asp:LinkButton>
<asp:RegularExpressionValidator ID="regexSender" runat="server"
ControlToValidate="txtMailAdd" ErrorMessage="Incorrect Mailing Address"
ValidationExpression="\w+([-+.]\w+)*@\w+([-.]\w+)*\.\w+([-.]\w+)*"
ValidationGroup="sendemail"></asp:RegularExpressionValidator>
</td>
</tr>
<tr>
<td class="style15">
SMTP IP
</td>
<td>
<asp:TextBox ID="txtSMTP" runat="server" Width="414px" CssClass="Textbox1"></asp:TextBox>
<asp:LinkButton ID="lbEdit2" runat="server" onclick="lbEdit2_Click"> Edit
</asp:LinkButton>
<asp:RegularExpressionValidator ID="regexSMTP" runat="server"
ControlToValidate="txtSMTP" ErrorMessage="IP Address is Incorrect"
ValidationExpression="(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)"
ValidationGroup="sendemail"></asp:RegularExpressionValidator>
</td>
</tr>
<tr>
<td class="style15">
SMTP AUTHENTICATION
</td>
<td>
<asp:CheckBox ID="cbxAuth" runat="server" />
</td>
</tr>
<tr>
<td class="style16">
</td>
<td class="style11">
User Name
<asp:TextBox ID="txtUsName" runat="server" Enabled="false" Width="299px" CssClass="Textbox1"></asp:TextBox>
<asp:LinkButton ID="lbEdit3" runat="server" OnClick="lbEdit3_Click"> Edit
</asp:LinkButton>
<br />
Password
<asp:TextBox ID="txtPassword" runat="server" TextMode="Password" Width="300px" Enabled="false"
CssClass="Textbox1"></asp:TextBox>
<asp:LinkButton ID="lbEdit4" runat="server" OnClick="lbEdit4_Click"> Edit
</asp:LinkButton>
<asp:RequiredFieldValidator ID="reqPass" runat="server" ControlToValidate="txtPassword"
Display="Dynamic" ErrorMessage="Enter a Password" ValidationGroup="sendemail"></asp:RequiredFieldValidator>
<asp:RequiredFieldValidator ID="reqUserMail" runat="server" ControlToValidate="txtUsName"
Display="Dynamic" ErrorMessage="Enter a User Name" ValidationGroup="sendemail"></asp:RequiredFieldValidator>
</td>
</tr>
<tr>
<td class="style15"> RECEIVER </td>
<td> <asp:TextBox ID="txtReceiver" runat="server" CssClass="Textbox1" Width="414px"></asp:TextBox>
<asp:LinkButton ID="lbEdit5" runat="server" OnClick="lbEdit5_Click"> Edit </asp:LinkButton>
</td>
</tr>
<tr>
<td class="style15">
TO MAIL
</td>
<td>
<asp:TextBox ID="txtTo" runat="server" CssClass="Textbox1" Width="414px"></asp:TextBox>
<asp:LinkButton ID="lbEdit6" runat="server" OnClick="lbEdit6_Click"> Edit
</asp:LinkButton>
<asp:RegularExpressionValidator ID="regexTo" runat="server"
ControlToValidate="txtTo" Display="Dynamic" ErrorMessage="Enter an E-Mail Address"
ValidationExpression="\w+([-+.]\w+)*@\w+([-.]\w+)*\.\w+([-.]\w+)*"></asp:RegularExpressionValidator>
<asp:RequiredFieldValidator ID="reqMailTo" runat="server"
ControlToValidate="txtTo" ErrorMessage="Enter a Mailing Address"></asp:RequiredFieldValidator>
</td>
</tr>
<tr>
<td class="style15">
SUBJECT
</td>
<td class="style11">
<asp:TextBox ID="txtSub" runat="server" Width="414px" CssClass="Textbox1"></asp:TextBox>
</td>
</tr>
<tr>
<td class="style15">
CONTENT
</td>
<td>
<asp:TextBox ID="txtBody" runat="server" Width="414px" CssClass="Textbox1" Columns="10"
Rows="10" TextMode="MultiLine"></asp:TextBox>
</td>
</tr>
<tr>
<td class="style16">
ATTACHMENT
</td>
<td>
<asp:FileUpload ID="fupAttach" runat="server" CssClass="Textbox1"
Width="414px" />
</td>
</tr>
<tr>
<td colspan="2">
</td>
</tr>
<tr>
<td colspan="2">
</td>
</tr>
<tr>
<td colspan="2">
<tr>
<td colspan="2" style="margin-left: 40px" align="center">
<asp:Label ID="lblMailFail" runat="server" ForeColor="Red"></asp:Label>
</td>
</tr>
</td>
</tr>
<tr>
<td colspan="2" align="center" class="style12" style="margin-left: 500px">
<asp:Button ID="btnSMail" runat="server" CssClass="btn" Text="Send"
onclick="btnSMail_Click" />
<asp:Button ID="btnCancelMail" runat="server" CssClass="btn" Text="Cancel" />
</td>
</tr>
<tr>
<td colspan="2">
</td>
</tr>
</table>
</asp:View>
出现这种情况有什么好理由？
答案 0 :(得分：1)
一方面，您将check作为参数checkbox(check)传递给事件onload，并再次在此行中定义check：
var check = document.getElementById("cbxAuth"); //<- error from this line
此外，为什么不为事件onload和onchange指定一些不同的有意义的函数名称。
ADDED ，在使用标记编辑问题后，cbxAuth是服务器控件，因此您需要获取其ClientID以获取其在JavaScript中的引用。这样：
var chkbox = document.getElementById("<%= cbxAuth.ClientID %>");
对于另一部分，简单地将函数名称更改为一些有意义的名称，如前所述。
window.onload = function OnWindowLoad(check) {
var chkbox = document.getElementById("<%= cbxAuth.ClientID %>");
if (chkbox)
{
chkbox.onchange = function OnCheckBoxChange(chkbox) {
// ... rest of your code
};
}
};