Page.IsStartupScriptRegistered Method
Determines if the client startup script is registered with the Page object.
[Visual Basic] Public Function IsStartupScriptRegistered( _ ByVal key As String _ ) As Boolean [C#] public bool IsStartupScriptRegistered( string key ); [C++] public: bool IsStartupScriptRegistered( String* key ); [JScript] public function IsStartupScriptRegistered( key : String ) : Boolean;
Parameters
- key
- The string key of the startup script to search for.
Return Value
true if the startup script is registered; otherwise, false.
Remarks
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.
Example
[Visual Basic, C#] The following example demonstrates the use of the RegisterStartupScript method in conjunction with IsStartupScriptRegistered method. If the ECMAScript written in the code-declaration block has not already been registered, as tested by IsStartupScriptRegistered, the a RegisterStartupBlock call is made.
[Visual Basic] <html> <head> <script language="VB" runat="server"> public Sub Page_Load(Sender As Object,e As EventArgs) ' Form the script to be registered at client side. Dim scriptString As String = "<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>" If(Not Me.IsStartupScriptRegistered("Startup")) Then Me.RegisterStartupScript("Startup", scriptString) End If End Sub </script> </head> <body topmargin="20" leftmargin="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> </form> </body> </html> [C#] <html> <head> <script language="C#" runat="server"> public void Page_Load(Object sender, EventArgs e) { // 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>"; if(!this.IsStartupScriptRegistered("Startup")) this.RegisterStartupScript("Startup", scriptString); } </script> </head> <body topmargin="20" leftmargin="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> </form> </body> </html>
[C++, JScript] No example is available for C++ or JScript. To view a Visual Basic or C# example, click the Language Filter button
in the upper-left corner of the page.
Requirements
Platforms: Windows 2000, Windows XP Professional, Windows Server 2003 family
See Also
Page Class | Page Members | System.Web.UI Namespace | RegisterStartupScript