This documentation is archived and is not being maintained.

Page.IsClientScriptBlockRegistered Method

Determines if the client script block is registered with the page.

[Visual Basic]
Public Function IsClientScriptBlockRegistered( _
   ByVal key As String _
) As Boolean
[C#]
public bool IsClientScriptBlockRegistered(
 string key
);
[C++]
public: bool IsClientScriptBlockRegistered(
 String* key
);
[JScript]
public function IsClientScriptBlockRegistered(
   key : String
) : Boolean;

Parameters

key
The string key of the client script to search for.

Return Value

Returns true if the script block is registered; otherwise, false.

Remarks

Call this method before calling Page.RegisterClientScriptBlock 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 RegisterClientScriptBlock method in conjunction with IsClientScriptBlockRegistered method. If the ECMAScript written in the code-declaration block has not already been registered, as tested by IsClientScriptBlockRegistered, the a RegisterClientScriptBlock call is made.

[Visual Basic] 
<html>
  <head>
     <script language="VB" runat="server">
    Sub Page_Load( sender as Object,e as EventArgs) 
         
       'Form the script that is to be registered at client side.
        Dim scriptString as String = "<script language=JavaScript> function DoClick() {"
        scriptString += "myForm.show.value='Welcome to Microsoft .NET'}<"
        scriptString += "/"
        scriptString += "script>"
      
            If(Not IsClientScriptBlockRegistered("clientScript"))
        RegisterClientScriptBlock("clientScript", scriptString)
        End If
     End Sub
     </script>
  </head>
  <body topmargin="20" leftmargin="10">
     <form id="myForm" runat="server">
        <input type="text" id="show" style="width=200">
      <input type="button" value="ClickMe" onclick="DoClick()">
     </form>
  </body>
</html>

[C#] 
<html>
  <head>
    <script language="C#" runat="server">

     public void Page_Load(Object sender, EventArgs e) {

       // Form the script that is to be registered at client side.
       String scriptString = "<script language=JavaScript> function DoClick() {";
       scriptString += "myForm.show.value='Welcome to Microsoft .NET'}<";
       scriptString += "/";
       scriptString += "script>";

           if(!this.IsClientScriptBlockRegistered("clientScript"))
              this.RegisterClientScriptBlock("clientScript", scriptString);
     }

     </script>
  </head>
  <body topmargin="20" leftmargin="10">
     <form id="myForm" runat="server">
        <input type="text" id="show" style="width=200"> <input type="button" value="ClickMe" onclick="DoClick()">
     </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 Language Filter 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 | RegisterClientScriptBlock

Show: