how to call javascript function in c#

Write function this way

protected void print_click(object sender,eventargs e)
{
  //when i click this button i need to call javascript function
    System.Text.StringBuilder sb = new System.Text.StringBuilder();
            sb.Append(@"<script language='javascript'>");
            sb.Append(@"example();");
            sb.Append(@"</script>");
     System.Web.UI.ScriptManager.RegisterStartupScript(this, this.GetType(), "JCall1", sb.ToString(), false);
}

Read all of the existing answers, but first, understand one fundamental things: you cannot even talk about "call".

C# is on the server side, Javascript — on the client side. It could be anything but "call". What is it? First of all, you need to understand some basics of the Web functionality. All server-side code does is receiving HTTP request from client side, process it, and then generate HTTP response and send it to client side. You can generate any thinkable content. And part of the content can be Javascript. You just generate Javascript, possibly in a parametrized way, using some data. How you do it? This is a separate question. You can generate HTTP response directly, or use RegisterStartupScript, or anything. This is the essence of how it works.

—SA

Hi,

Try this

string str="<script>alert(\"ok\");</script>";
Page.ClientScript.RegisterStartupScript(this.GetType(), "Script", str, false);

here is two method. here you have not cleared that 1. after executing java function do you want to some in print_click event in cs. or 2. In print_click event excecute than you want js function

in 1. condition you can write simply

print.Attributes.Add("onclick", "example();");

in 2. condition you can write

protected void print_click(object sender,eventargs e)
{
  //when i click this button i need to call javascript function

ScriptManager.RegisterStartupScript(Page, GetType(), "JsStatus", "example();", true);

}

Hi,

Use this code which i have used and it's working

protected void print_click(object sender,eventargs e)
{
ClientScript.RegisterStartupScript(this.GetType(), "print", "<script>example();</script>");
}

All solutions you added are excellent in syntax-level. But you should remember, there's a delay in runtime-level between sever-side and client-side scripts when you're trying to run the script within the PageLoad. So you should give enough time to the ASP.net server side to regenerate the webpage, as it should be ...

ClientScript.RegisterStartupScript(this.GetType(),
                                   "script",
                                   "setTimeout(YourFunction1, 1000);",
                                   true);

I think 1s is enough for regeneration of a little form... increase it depending on your need.