ClientScriptManager.IsOnSubmitStatementRegistered Method (String)
Determines whether the OnSubmit statement is registered with the Page object using the specified key.
Assembly: System.Web (in System.Web.dll)
Call this method before calling the RegisterOnSubmitStatement method to avoid registering duplicate OnSubmit statements. This is particularly important if the statement requires a large amount of server resources to create.
A statement is uniquely identified by its key and its type. Statements with the same key and type are considered duplicates.
Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)
The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.