JavaScript: Alert.Show(”message”) from ASP.NET code-behind

using System.Web;
using System.Text;
using System.Web.UI;

///

/// A JavaScript alert
///

public static class Alert
{

///

/// Shows a client-side JavaScript alert in the browser.
///

/// The message to appear in the alert.
public static void Show(string message)
{
// Cleans the message to allow single quotation marks
string cleanMessage = message.Replace("'", "\\'");
string script = "";

// Gets the executing web page
Page page = HttpContext.Current.CurrentHandler as Page;

// Checks if the handler is a Page and that the script isn't allready on the Page
if (page != null && !page.ClientScript.IsClientScriptBlockRegistered("alert"))
{
page.ClientScript.RegisterClientScriptBlock(typeof(Alert), "alert", script);
}
}
}
Demonstration

That class of only 30 lines of code enables us to add a JavaScript alert to any page at any time. Here is an example of a Button.Click event handler that uses the method for displaying status messages.

void btnSave_Click(object sender, EventArgs e)
{
try
{
SaveSomething();
Alert.Show("You document has been saved");
}
catch (ReadOnlyException)
{
Alert.Show("You do not have write permission to this file");
}
}