https://learn.microsoft.com/en-us/dotnet/api/system.web.ui.webcontrols.customvalidator.clientvalidationfunction?view=netframework-4.7.2
CustomValidator.ClientValidationFunction Property (System.Web.UI.WebControls) | Microsoft Learn
Gets or sets the name of the custom client-side script function used for validation.
property systemweb uimicrosoftlearn
https://learn.microsoft.com/en-us/dotnet/api/system.web.ui.webcontrols.customvalidator.clientvalidationfunction?view=netframework-4.8.1&redirectedfrom=MSDN
CustomValidator.ClientValidationFunction Property (System.Web.UI.WebControls) | Microsoft Learn
Gets or sets the name of the custom client-side script function used for validation.
property systemweb uimicrosoftlearn