Web alert in c#script

Question

I am developing a web system on Asp.net and came across a problem.

On the return of your Catchs, I return an error through an Alert to the user thus:

try{
...
}
catch(Exception ex){
    Response.Write("<script>alert('Erro ao adicionar valores no banco.');</script>");
}

The problem is that I also use a class. Cs that is not related to any page, and it also needs to return some errors, but if I use "Response.Write" nothing happens.

How could I return these errors in the browser?

I have tried the following ways, but have not succeeded:

• Response.write
• page.ClientScript.RegisterClientScriptBlock()
• ScriptManager.RegisterStartupScript()