Javascript asp.net错误为“0”；“字符文字”中的字符太多；

我在DropDownList的索引更改上调用javascript，我的操作如下

<asp:DropDownList ID="DropDownList1" runat="server" AutoPostBack="True" 
OnSelectedIndexChanged="toggleVisibility('Button1');">

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有人能帮我解决这个问题吗？

OnSelectedIndexChanged

是一个服务器端事件，如果您想在客户端切换可见性，则需要设置OnClientClick并设置AutoPostBack=“false”

对于服务器端

<asp:DropDownList ID="DropDownList1" runat="server" AutoPostBack="True" 
OnSelectedIndexChanged="toggleVisibility">

protected object toggleVisibility(object sender, EventArgs e)
{
   Button1.Visible = !Button1.Visible;
}

<asp:DropDownList ID="DropDownList1" runat="server" AutoPostBack="True" 
OnSelectedIndexChanged="toggleVisibility">

protected object toggleVisibility(object sender, EventArgs e)
{
   Button1.Visible = !Button1.Visible;
}

DropDownList1.Attributes.Add("onchange","toggleVisibility('Button1');");