从代码beind（C＃）catch块调用JavaScript函数

Question

I am trying to call a JavaScript function from my ascx control code behind in the catch block. I have tried the below two ways but they don't seem to work.

1. Page.ClientScript.RegisterClientScriptBlock(typeof(string), "script", "test();", true);

2. ScriptManager.RegisterStartupScript(Page, GetType(), "err_msg", "alert('error');", true);

The function is called if I place the code Under "PageLoad" but doesn't get called when placed in catch block.Should I do any different to call a JavaScript function from catch block. Please suggest.

Thanks

Answer 1

Have you tried this?

Page.ClientScript.RegisterStartupScript(typeof(string), "script", "test();", true);

I cant recall off the top of my head if that is equivalent to the ScriptManager option in the question.

Also you need to make sure that the "script key" value you are passing in is unique otherwise asp.net will discard all but the first instance of the registered script with the same key.

Answer 2

Javascript does not like at all special characters and NewLine (\\r\\n) characters. Replace all of those and it will work.

Example:

string test = msgError.Replace("'", "");
test = Server.HtmlEncode(test).Replace(Environment.NewLine, "<br />");
Page.ClientScript.RegisterStartupScript(
            typeof(string),
            "MyKeyCatch",
            //script,
            "showErrorMessage('"+test+"');",
            true);

Answer 3

might want to try this: .cs

public String ScriptToRun = "test();";

.aspx

$(document).ready(function() {<%=ScriptToRun %>}); //or you can register event to document mannually

Remember that whatever you done in backend is going to generate HTML, Css& javascript to browser.

update: I tried the following code, it works in my case. could you please provide more detail? .cs

public String script = "";

protected void Page_Load(object sender, EventArgs e)
{
    throwExcep();
}

private void throwExcep()
{
    try
    {
        throw new NotImplementedException();
    }
    catch (Exception e)
    {
        script = "console.log('exception throws from backend message: ["+e.Message+"]')";
    }
}

.aspx:

<script>
    $(document).ready(function(){
        <%=script  %>
    });
  </script>

Answer 4

What is the catch block for and where is it?

If code in a catch block is executed it usually means that something failed, maybe that failure also is the reason the JS call does not go through.