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Page.IsStartupScriptRegistered Method

NOTE: This API is now obsolete.

Determines whether the client startup script is registered with the Page object.

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

[ObsoleteAttribute("The recommended alternative is ClientScript.IsStartupScriptRegistered(string key).")]
public bool IsStartupScriptRegistered(
	string key


Type: System.String

The string key of the startup script to search for.

Return Value

Type: System.Boolean
true if the startup script is registered; otherwise, false.

Call this method before calling Page.RegisterStartupScript to avoid unnecessarily assembling the client-side script. This is particularly important if the script requires a large amount of server resources to create.

The IsStartupScriptRegistered method has been deprecated. Use the IsStartupScriptRegistered method in the ClientScriptManager class.

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 IsStartupScriptRegistered, 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