在 DropDownList SelectedIndexChanged 事件上调用 JavaScript 函数：
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Call JavaScript function on DropDownList SelectedIndexChanged Event:
提问by thevan
I have written one JavaScript function as follows:
我编写了一个 JavaScript 函数，如下所示：
function CalcTotalAmt()
{
----------
-----------
}
I have one DropDownList,
我有一个 DropDownList，
<asp:DropDownList ID="ddl" runat="server" AutoPostBack="true" OnSelectedIndexChanged="ddl_SelectedIndexChanged"></asp:DropDownList>
I need to call the above JavaScript function in the DropDownList's SelectedIndexChanged Event. I tried like below;
我需要在 DropDownList 的 SelectedIndexChanged 事件中调用上述 JavaScript 函数。我试过如下;
protected void ddl_SelectedIndexChanged(object sender, EventArgs e)
{
ddl.Attributes.Add("onchange", "return CalcTotalAmt();");
}
But the JavaScript function is not executing. How to call the JavaScript function in DropDownList Change Event?
但是 JavaScript 函数没有执行。如何在 DropDownList Change Event 中调用 JavaScript 函数？
采纳答案by Kapil Khandelwal
First Method: (Tested)
第一种方法：（已测试）
Code in .aspx.cs:
.aspx.cs 中的代码：
protected void Page_Load(object sender, EventArgs e)
{
ddl.SelectedIndexChanged += new EventHandler(ddl_SelectedIndexChanged);
if (!Page.IsPostBack)
{
ddl.Attributes.Add("onchange", "CalcTotalAmt();");
}
}
protected void ddl_SelectedIndexChanged(object sender, EventArgs e)
{
//Your Code
}
JavaScript function: return true from your JS function
JavaScript 函数：从你的 JS 函数返回 true
function CalcTotalAmt()
{
//Your Code
}
.aspx code:
.aspx 代码：
<asp:DropDownList ID="ddl" runat="server" AutoPostBack="true">
<asp:ListItem Text="a" Value="a"></asp:ListItem>
<asp:ListItem Text="b" Value="b"></asp:ListItem>
</asp:DropDownList>
Second Method: (Tested)
第二种方法：（已测试）
Code in .aspx.cs:
.aspx.cs 中的代码：
protected void Page_Load(object sender, EventArgs e)
{
if (Request.Params["__EVENTARGUMENT"] != null && Request.Params["__EVENTARGUMENT"].Equals("ddlchange"))
ddl_SelectedIndexChanged(sender, e);
if (!Page.IsPostBack)
{
ddl.Attributes.Add("onchange", "CalcTotalAmt();");
}
}
protected void ddl_SelectedIndexChanged(object sender, EventArgs e)
{
//Your Code
}
JavaScript function: return true from your JS function
JavaScript 函数：从你的 JS 函数返回 true
function CalcTotalAmt() {
//Your Code
__doPostBack("ctl00$MainContent$ddl","ddlchange");
}
.aspx code:
.aspx 代码：
<asp:DropDownList ID="ddl" runat="server" AutoPostBack="true">
<asp:ListItem Text="a" Value="a"></asp:ListItem>
<asp:ListItem Text="b" Value="b"></asp:ListItem>
</asp:DropDownList>
回答by Imran Balouch
Or you can do it like as well:
或者你也可以这样做：
<asp:DropDownList ID="ddl" runat="server" AutoPostBack="true" onchange="javascript:CalcTotalAmt();" OnSelectedIndexChanged="ddl_SelectedIndexChanged"></asp:DropDownList>
回答by Cyberpks
You can use the ScriptManager.RegisterStartupScript();to call any of your javascript event/Client Event from the server. For example, to display a message using javascript's alert();, you can do this:
您可以使用ScriptManager.RegisterStartupScript();来从服务器调用任何 javascript 事件/客户端事件。例如，要使用 javascript 显示消息alert();，您可以执行以下操作：
protected void ddl_SelectedIndexChanged(object sender, EventArgs e)
{
Response.write("<script>alert('This is my message');</script>");
//----or alternatively and to be more proper
ScriptManager.RegisterStartupScript(this, this.GetType(), "callJSFunction", "alert('This is my message')", true);
}
To be exact for you, do this...
准确地说，请执行此操作...
protected void ddl_SelectedIndexChanged(object sender, EventArgs e)
{
ScriptManager.RegisterStartupScript(this, this.GetType(), "callJSFunction", "CalcTotalAmt();", true);
}
