Javascript alert problem

I am trying to add an alert box so that the user can choose either Yes or No or Ok and Cancel, but it is not working correctly.I have to do a database check which is done in c sharp not just link that function to a button clicked event. I开发者_Python百科t is my first time I am trying to do this. I am using visual studio 2010. I am not sure if my code is correct. Can anyone please guide me if I am mistaken.

         private void AlertWithConfirmation()
           {
            Response.Write("<script language='javascript'>"); 
            Response.Write("function onsub() "); 
            Response.Write("{ "); 
            Response.Write("return confirm(\"Are you sure?\")"); 
            Response.Write("} "); 
            Response.Write("</script>");
           }

This is my full C# Code:

    protected void Import_Click(object sender, EventArgs e)
    {
        if (!Validation.ValidateDateFormat(dateField.Text))
        {
            errorMessageLabel.Text = "Invalid Date Format, for example: 1/1/2011 should be 01/01/2011";
        }
        else
        {
            //Validation to check if data is already imported
            if (BusinessLayerHandler.isImported(dateField.Text) == false)
            {
                try
                {
                    if (BusinessLayerHandler.isInProgress(dateField.Text)== true)
                    {
                        AlertWithConfirmation();
                    }
                }
                catch
                {
                    //catch error
                }
            }
            else if (BusinessLayerHandler.isImported(dateField.Text) == true)
            {
                Alert("That date was already imported");
            }
        }

your code is absolutely correct. only syntax error. just remove "\" before starting the double quotes in the line-> Response.Write("return confirm(\"Are you sure?\")");
replace with this line
Response.Write("return confirm("Are you sure?\")");

I don't see where you're calling the function. Why not have the function always on the page and dynamically add the function call to the button in the code behind?

Something like:

button.Attributes.Add("onclick", "onsub();");