使用 Javascript 调用 C# 方法

Question

I am trying to access a method in my code behind called "Button1_Click" using Javascript, I think there is something wrong in my code below because currently I have to click twice in order for the method to trigger, one click doesn't trigger the method.

My Test Code:

// Javascript

<script type="text/javascript">
 function CallMe() { document.getElementById('<%= ButtonHidden.ClientID %>').click(); }
</script>

// Markup

<asp:Button ID="ButtonVisible" runat="server" Text="Test Button"
  OnClientClick="CallMe();"/>
<asp:Button ID="Button1" runat="server" style="display:none;" Text="Click"
  OnClick="Button1_Click"/>

// Code Behind Method

protected void Button1_Click(object sender, EventArgs e)
{
    Response.Redirect("http://google.com");
}

Am I missing something?

Answer 1

You could use the OnClientClick property of the Button:

<asp:button id="Button1"
   text="Test Button"
   onclientclick="CallMe()"
   runat="server" onclick="Button1_Click" />

Then you don't need another (hidden) button.

Your CallMe() method should then return either true (if everything is OK) or false (to cancel the postback).

Answer 2

Instead of using javascript why not simply assign the same server click handler for both buttons:

<asp:Button 
    ID="ButtonVisible" 
    runat="server" 
    Text="Test Button" 
    OnClick="Button1_Click" />

<asp:Button 
    ID="Button1" 
    runat="server" 
    style="display:none;" 
    Text="Click" 
    OnClick="Button1_Click" />

---

UPDATE:

A better solution would be to have your javascript function return a boolean value depending on whether some conditions are met which will execute the server handler:

<script type="text/javascript">
    function CallMe() {         
        if (some condition) {
            return true; // allow the server to be called
        }
        return false;
    }
</script>

and then use both OnClick and OnClientClick on the button:

<asp:Button 
    ID="ButtonVisible" 
    runat="server" 
    Text="Test Button" 
    OnClientClick="return CallMe();"
    OnClick="Button1_Click" />