function preguntar(){
  const swalWithBootstrapButtons = Swal.mixin({
  confirmButtonClass: 'btn btn-success',
  cancelButtonClass: 'btn btn-danger',
  buttonsStyling: false,
})

swalWithBootstrapButtons({
  title: 'Desea guardar los registros?',
  text: "No podra cancelar la operacion",
  type: 'warning',
  showCancelButton: true,
  confirmButtonText: 'Si, Guardar',
  cancelButtonText: 'No, Cancelar!',
  reverseButtons: true
 }).then((result) => {

 if (result.value) {
   return true
 } else if (
  // Read more about handling dismissals
   result.dismiss === Swal.DismissReason.cancel
 ) {
    return false
  }
})
 }

Page.ClientScript.RegisterStartupScript(Page.ClientScript.GetType(), "onLoad", "preguna();", true);

if(funcion==true){
 llamar_funcion_de_asp();
}else{
  --terminar_instruccion.
 }