Setting date using milliseconds

I currently have a date picker on the client side. Once a date is selected the date in milliseconds is sent to my node app. the problem is i am getting Invalid Date for new Date(milliseconds)

the milliseconds sent look like this ( 1347433200000 ) my code is as fallows

app.get('/dashboard/date/:date', function(req, res){
    console.log(new Date(req.params.date));
    var start = new Date(req.params.date);
    var end = new Date(req.params.date).add({hours:23, minutes:59, seconds: 59, milliseconds: 999});
    console.log(start);
    console.log(end);

    Appointments.find({'scheduled' : {"$gte": start, "$lt": end}}, function(err, list){
        res.render('templates/list',{ layout: false, appointments: list });
    });
});

req.params.date is a string so you need to convert it to a number before passing it to the Date constructor. Try this instead:

var start = new Date(Number(req.params.date));