format a column field as a date

[MesquiteGIS]

I'm having trouble getting one of my fields to format as a date. I've defined my columns under gridOptions in the search.js file. My code looks like this:

    createFeatureTable: function () {
        var attributeTable = dijit.byId('attributesContainer_widget');
        this.queryID = this.queryID + 1;

        var tables = [
            {
                title: this.i18n.searchTXT + ' ' + this.queryID,
                topicID: this.queryID,
                gridOptions: {
                    columns:[
                                { label: 'Section ID', field: 'SectionID', width: 100,},
                                { label: 'Street Name', field: 'FullStreetName', width: 170, },
                                { label: 'Begin Point', field: 'BeginPoint', width: 170, },
                                { label: 'End Point', field: 'EndPoint', width: 170, },
                                { label: 'Surface Condition Rating', field: 'SurfaceConRating', width: 100, },
                                { label: 'Drainage Rating', field: 'DrainageRating', width: 150, },
                                //{ label: 'Evaluated', field: 'EvalDate', width: 150,},
                                { label: 'Evaluated By', field: 'EvalBy', width: 100, },
                                {
                                field: 'EvalDate',
                                label: 'Evaluated',
                                get: function (object) { // allow export as a proper date
                                    return new Date(object.EvalDate);
                                },
                                formatter: formatDateTime
                            }
                    ],
                },
                queryOptions: {
                    queryParameters: {
                        url: this.selectionIdentifyLayerDijit.item.url + '/' + this.selectionIdentifyLayerDijit.item.subID,
                        maxAllowableOffset: 100,
                        where: this.objectiidfield + " IN (" + this.ids + " )"
                    },
                    idProperty: this.objectiidfield
                }
            }
        ];

        var table = attributeTable.addTab(tables[0]);

    },