How to show MessageBox on

if I need to show a MessageBox on my ASP.NET WebForm, how to do it?

I try:"dd");

But it’s not working.


Thank you for visiting the Q&A section on Magenaut. Please note that all the answers may not help you solve the issue immediately. So please treat them as advisements. If you found the post helpful (or not), leave a comment & I’ll get back to you as soon as possible.

Method 1

MessageBox doesn’t exist in ASP.NET. If you need functionality in the browser, like showing a message box, then you need to opt for javascript. ASP.NET provides you with means to inject javascript which gets rendered and executed when the html sent to the browser’s loaded and displayed. You can use the following code in the Page_Load for example:

Type cstype = this.GetType();

// Get a ClientScriptManager reference from the Page class.
ClientScriptManager cs = Page.ClientScript;

// Check to see if the startup script is already registered.
if (!cs.IsStartupScriptRegistered(cstype, "PopupScript"))
    String cstext = "alert('Hello World');";
    cs.RegisterStartupScript(cstype, "PopupScript", cstext, true);

This sample’s taken from MSDN.

Method 2

There is pretty concise and easy way:

Response.Write("<script>alert('Your text');</script>");

Method 3

Messagebox is for windows only. You have to use Javascript


Method 4

You could just simply write but you have to use JavaScript regardless.

Page.ClientScript.RegisterStartupScript(Page.GetType(), "Message Box", "<script language = 'javascript'>alert('dd')</script>");

Method 5

One of the options is to use the Javascript.

Here is a quick reference where you can start from.

Javascript alert messages

Method 6

It’s true that"dd"); is not a part of using System.Web;,

I felt the same situation for most of time. If you want to do this then do the following steps.

  • Right click on project in solution explorer
  • go for add reference, then choose .NET tab
  • And select, (press ‘s’ to find quickly)

u can get the namespace, now u can use"dd");

But I recommend to go with javascript alert for this.

Method 7

Message box is only defaultly available for windows form application.If you want to use the message box resource the you would have to use
‘using’ to enable the message box for web forms mode.

Method 8

I took the code from the brilliant @KrisVanDerMast and made it wrapped up in a static method that can be called as many times as you want on the same page!

/// <summary>
/// Shows a basic MessageBox on the passed in page
/// </summary>
/// <param name="page">The Page object to show the message on</param>
/// <param name="message">The message to show</param>
/// <returns></returns>
public static ShowMessageBox(Page page, string message)
    Type cstype = page.GetType();

    // Get a ClientScriptManager reference from the Page class.
    ClientScriptManager cs = page.ClientScript;

    // Find the first unregistered script number
    int ScriptNumber = 0;
    bool ScriptRegistered = false;
        ScriptRegistered = cs.IsStartupScriptRegistered(cstype, "PopupScript" + ScriptNumber);
    } while (ScriptRegistered == true);

    //Execute the new script number that we found
    cs.RegisterStartupScript(cstype, "PopupScript" + ScriptNumber, "alert('" + message + "');", true);

Method 9

You may use MessageBox if you want but it is recommended to use alert (from JavaScript) instead.

If you want to use it you should write:


Note that you must specify the namespace.

All methods was sourced from or, is licensed under cc by-sa 2.5, cc by-sa 3.0 and cc by-sa 4.0

0 0 votes
Article Rating
Notify of

Inline Feedbacks
View all comments
Would love your thoughts, please comment.x