why does javascript not rendering any function when deployed

Question

I am using onkeychange javascript Email field

 <asp:TextBox ID="Email" runat="server" onkeyup="change();"></asp:TextBox>

function change(){
        var Email= document.getElementById('#ctl00_ctl40_g_e7fed4bf_b25a_4a8a_943d_e31932556a9e_FBACreateUserWizard_CreateUserStepContainer_Email');
        var UserName= document.getElementById('#ctl00_ctl40_g_e7fed4bf_b25a_4a8a_943d_e31932556a9e_FBACreateUserWizard_CreateUserStepContainer_UserName');
        UserName.value=Email.value;
     }

and I rendered in my c#

 protected override void RenderContents(HtmlTextWriter writer)
        {

System.Text.StringBuilder sb2 = new System.Text.StringBuilder();
sb2.AppendLine(@"<script language='javascript'>");
sb2.AppendLine(@"function change(){");
sb2.AppendLine(@"var Email= document.getElementById('#ctl00_ctl40_g_e7fed4bf_b25a_4a8a_943d_e31932556a9e_FBACreateUserWizard_CreateUserStepContainer_Email');");
sb2.AppendLine(@"var UserName= document.getElementById('#ctl00_ctl40_g_e7fed4bf_b25a_4a8a_943d_e31932556a9e_FBACreateUserWizard_CreateUserStepContainer_UserName');");
sb2.AppendLine(@"UserName.value=Email.value;");
sb2.AppendLine(@" }");
sb2.Append(@"</script>");

if (!Page.ClientScript.IsStartupScriptRegistered("JSScript"))
{
    Page.ClientScript.RegisterStartupScript(this.GetType(), "JSScript", sb2.ToString());

}

when I deploy the function is not performing I can see the code rendered to the page.

Answer 1

i think you need to change this line

if (!Page.ClientScript.IsStartupScriptRegistered("JSScript"))
            {
                Page.ClientScript.RegisterStartupScript(this.GetType(), "JSScript", sb2.ToString());

            }

to this.

//it will Render the function definition. 
if (!ClientScript.IsClientScriptBlockRegistered("JSScript")) 
{
   ClientScript.RegisterClientScriptBlock(this.GetType(), "JSScript", sb2.ToString()); 
}

for more to know about it refer this.