If you are talking of ASP.NET, you can add "DefaultButton"
property for the page.
In ASP.NET 2.0 onwards, it's said to have "Default Button" defined for the page. By simply specifying the
property to the ID of the
, whose event you want to fire, your job is done.
The defaultbutton property can be specified at the Form level in the form tag as well as at panel level in the
definition tag. The form level setting is overridden when specified at the panel level, for those controls that are inside the panel
ASP.NET DefaultButton Property
Sample usage of Default button