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Show Alert Message Box from Code-behind in Asp.net C# Vb

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How to show alert message box from code-behind in asp.net c# vb.net?
How to show alert message box from code-behind in asp.net c# vb.net?

In my previous tutorials, I’d explained how to show alert message from client-side, how to call javascript function from code-behind, confirm message box example using javascript and more cracking tutorials on Asp.net, JavaScript, jQuery here.

Now here in this tutorial, I’ll explain how to show alert message box from server-side or code-behind in asp.net using c# or vb.net with example code.

Show Alert Message from Code-behind – [.aspx]

Following is the complete HTML Markup code that I used in my .aspx page for this demonstration:

<html xmlns="http://www.w3.org/1999/xhtml">
<head id="Head1" runat="server">
    <title>How to show alert message from code-behin in Asp.net</title>
    <script type="text/javascript">
        function alertMessage() {
            alert('JavaScript Function Called!');
        }
    </script>
</head>
<body>
    <form id="form1" runat="server">
        <h4>Show alert message from code-behin in Asp.net</h4>
        <div>
            <asp:Button ID="btnClientSide" runat="server" OnClientClick="alertMessage()"
                Text="Client-side" />
            <asp:Button ID="btnServerSideMethod1" runat="server" Text="Server-side(Method1)"
                OnClick="btnServerSideMethod1_Click" />
            <asp:Button ID="btnServerSideMethod2" runat="server" Text="Server-side(Method2)"
                OnClick="btnServerSideMethod2_Click" />
        </div>
    </form>
</body>
</html>

You can see, i’d added OnClientClick=”alertMessage()” when calling function from client-side. In case of calling javascript function from server-side or code-behind, we need OnClick event as OnClick=”btnServerSideMethod1_Click” and OnClick=”btnServerSideMethod2_Click”.

We need to use ScriptManager.RegisterStartupScript() method to achieve this. Here is the syntax for this method:

ScriptManager.RegisterStartupScript(Control control, Type type, string key, string script, bool addScriptTags);

Now define that event in code-behind as shown below.

Show Alert Message From Code-behind In C# – [.cs]

Following is the C# code:

//This method is used when you defined javascript function and want to call it
//So call pre-defined method this way
protected void btnServerSideMethod1_Click(object sender, EventArgs e) {
    ScriptManager.RegisterStartupScript(this, GetType(), "alertMessage", "alertMessage();", true);
}
    
//This method is used when you don't want to define javascript method client-side
//So call directly this way
protected void btnServerSideMethod2_Click(object sender, EventArgs e) {
    ScriptManager.RegisterStartupScript(this, GetType(), "alertMessage",
    "alert('Called from code-behind directly!');", true);
}

OR

If you are dealing with asp.net UpdatePanel and UpdateProgress, use the following code:

//Following statement is used to call pre-defined javascript function
protected void btnServerSide_Click(object sender, EventArgs e) {
    ScriptManager.RegisterStartupScript(myUpdatePanelID, myUpdatePanelID.GetType(), "myAlert",
    "alert('Called from code-behind directly!');", true);
}

Show Alert Message From Code-behind In Vb.net – [.vb]

Likewise, following is the Vb.net code to display or show alert message:

'This method is used when you defined javascript function and want to call it'
'So call pre-defined method this way'
Protected Sub btnServerSideMethod1_Click(ByVal sender As Object, ByVal e As EventArgs)
    ScriptManager.RegisterStartupScript(Me, Me.GetType(), "alertMessage", "alertMessage();", True)
End Sub

'This method is used when you don't want to define javascript method client-side'
'So call directly this way'    Protected Sub btnServerSideMethod2_Click(ByVal sender As Object, ByVal e As EventArgs)
    ScriptManager.RegisterStartupScript(Me, Me.GetType(), "alertMessage",
        "alert('Called from code-behind directly!');", True)
End Sub

OR

If you are dealing with asp.net UpdatePanel and UpdateProgress, use the following code:

'Following statement is used to call pre-defined javascript function'
Protected Sub btnServerSide_Click(ByVal sender As Object, ByVal e As EventArgs)
    ScriptManager.RegisterStartupScript(myUpdatePanelID, myUpdatePanelID.GetType(),
        "myAlert", "alert('Called from code-behind directly!');", True)
End Sub

Example Result

How to show alert message box from code-behind in asp.net c# vb.net?
How to show alert message box from code-behind in asp.net c# vb.net?
Previous articleShow Alert Message in JavaScript or jQuery
Next articleCall JavaScript Function from Code-behind in Asp.net C# Vb
Hi there, I am Mayank, the man behind Technical Mack. I started AspnetO with a motive to educate people on various programming languages ranging from beginners to expert level. Through this blog, I aim to provide more insightful content.

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