get las page when delete rows

gistfile1.js

$(document).on("click",
"#deleteSelection${cadenaAleatoria}",
function(){

$('.alertaGrillaResultado').css('display','inherit');
var selectedModels = grid.getSelectedModels();

if(selectedModels != ''){
	var respuesta = confirm('¿Desea retirar Horas de Equivalencia?');
	if(respuesta){
		_.each(selectedModels, function (model) {
			
		  model.trigger("backgrid:select", model, false);
		  var id = grid.collection.fullCollection.where({ id: model.id });
		  grid.removeRow(id);
		  $.get("@{delete()}/" + model.id, function (modelos) {});
		  $('.alertaGrillaResultado').html(
		  '<div class="alert alert-success">' + '<button type="button" class="close" data-dismiss="alert">&times;</button>' + "Se retiro la Hora de Equivalencia seleccionada" + '</div>'
		  );
		});
		//recargarGrid();
	}
	
	//alert("mi pagina "+collection.state.currentPage)
	//alert("ultima pagina "+collection.state.lastPage)
	
	if(collection.state.lastPage < collection.state.currentPage){
		collection.getLastPage();
	}
	
	/*if(collection.state.totalPages){
		collection.getLastPage();
	}
	*/
	
	//alert(collection.state.lastPage)
	//alert(collection.state.totalPages);
	//
	//collection.getPage(collection.state.currentPage)
	//alert(collection.state.currentPage)
	$('.alertaGrillaResultado').fadeOut(6000);
}
	
});