When I've used a formatter with my dGrids, I have it call a standalone function instead of doing the formatting work inline. Your modified code would be something like this:window.grid = new (declare([Grid, Selection])) ({ bufferRows:Infinity, columns: { "id": "ID", "vehicleId": "Vehicle ID", "velocity": {"label": "Speed (MPH)", "formatter":dojoNum.format}, "timestamp": {"label": "Time Stamp", "formatter":formatTimestamp} } }, "grid"); . . . . function formatTimestamp(value) { var inputDate = new Date(value); return dojo.date.locale.format(inputDate, { selector: 'date', datePattern: 'MM/dd/yyyy' }); }