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Page.RegisterStartupScript Method

NOTE: This API is now obsolete.

Emits a client-side script block in the page response.

Namespace:  System.Web.UI
Assembly:  System.Web (in System.Web.dll)

[ObsoleteAttribute("The recommended alternative is ClientScript.RegisterStartupScript(Type type, string key, string script).")]
public virtual void RegisterStartupScript(
	string key,
	string script


Type: System.String

Unique key that identifies a script block.

Type: System.String

Content of script that will be sent to the client.

Similar to the RegisterClientScriptBlock method, the RegisterStartupScript method emits the script just before the closing tag of the Page object's <form runat= server> element. Be sure to include opening and closing <script> elements around the script block string specified in the script parameter.

Because this method uses a key to identify the script block, the script block does not have to be emitted to the output stream each time it is requested by a different server control instance

Any script blocks with the same key parameter values are considered duplicates.


Remember to include HTML comment tags around your script so that it will not be rendered if the requesting browser does not support scripts.

The RegisterStartupScript method has been deprecated. Use the RegisterStartupScript method in the ClientScriptManager class instead.

The following code example demonstrates the use of the RegisterStartupScript method in conjunction with the IsStartupScriptRegistered method. If the ECMAScript written in the code declaration block has not already been registered, as determined by the IsStartupScriptRegistered method, then a RegisterStartupScript call is made.

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" 
<html xmlns="" >
    <title>Welcome to Microsoft .NET!</title>
<script language="C#" runat="server">
      public void Page_Load(Object sender, EventArgs e)

        if (!this.IsStartupScriptRegistered("Startup"))
          // Form the script to be registered at client side.
          String scriptString = "<script language=\"JavaScript\"> function DoClick() {";
          scriptString += "showMessage2.innerHTML='<h4>Welcome to Microsoft .NET!</h4>'}";
          scriptString += "function Page_Load(){ showMessage1.innerHTML=";
          scriptString += "'<h4>RegisterStartupScript Example</h4>'}<";
          scriptString += "/";
          scriptString += "script>";
          this.RegisterStartupScript("Startup", scriptString);
  <body style="margin-top:20; margin-left:10" onload="Page_Load()">
     <form id="myForm" runat="server">
        <span id="showMessage1"></span>
        <br />
        <input type="button" value="ClickMe" onclick="DoClick()" />
        <br />
        <span id="showMessage2"></span>

Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98

The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

.NET Framework

Supported in: 1.1, 1.0
Obsolete (compiler warning) in 3.5
Obsolete (compiler warning) in 3.5 SP1
Obsolete (compiler warning) in 3.0
Obsolete (compiler warning) in 3.0 SP1
Obsolete (compiler warning) in 3.0 SP2
Obsolete (compiler warning) in 2.0
Obsolete (compiler warning) in 2.0 SP1
Obsolete (compiler warning) in 2.0 SP2