nvd3 focus zoom brush values callback

index.js

//add data to the array like this
$scope.chartData=[{x:0,y:0}];

$scope.chartOptions = {
            "chart": {
                "type": 'linePlusBarChart',
                //...the other options...
                "callback": function(chart){
                                  chart.dispatch.on( 'brush', function (objBrush) {
                                    // objBrush.extent these are array index values!
                                    var intBegin=$scope.chartData[0].values[Math.round(objBrush.extent[0])].x;
                                    var intEnd=$scope.chartData[0].values[Math.round(objBrush.extent[1])].x;
                                    console.log(intBegin,intEnd);
                                });
  }
};