Display exception message through javascript alert in asp.net

Question

I am trying to show exception message through javascript alert box.

Here is the sample code.

public static void HandleException(Page page, Exception ex)
{
    string message = ex.Message.ToString();
    ScriptManager.RegisterClientScriptBlock(page, page.GetType(), "", "alert('"+message+"');", true);

}

It runs if i give literal values for the string variable. e.g.

string message = "Hello World";

But it fails if I give message = ex.Message;

Any Idea?

Answer 1

You need to encode it, for example using JavaScriptSerializer because if the message contains some escape characters like ' or " this will definitely break your javascript:

var message = new JavaScriptSerializer().Serialize(ex.Message.ToString());
var script = string.Format("alert({0});", message);
ScriptManager.RegisterClientScriptBlock(page, page.GetType(), "", script, true);

Answer 2

try    
{    
    //do some thing    
}    
catch (Exception ex)
{    
    Response.Write("<script language='javascript'>alert('" + 
        Server.HtmlEncode(ex.Message) + "')</script>");    
}

Answer 3

Does your ex.Message have any ' characters in it? They may need escaping.