Multidimensional object array javascript

multidimensionalObjectArray.js

var indexes = {};
            Data.forEach(function(indexPoint){
                var zoneIndexes = indexes[indexPoint.zoneId];

                if(zoneIndexes == null){
                    indexes[indexPoint.zoneId] = zoneIndexes = {};
                }

                zoneIndexes[indexPoint.date] = indexPoint.indexValue;
            });