Determine vertical direction of a touchmove

i'm trying to implement a touch listener for tablets to trigger some actions depending whether it touchmoved upwards or downwards.

I tried the native listener:

($document).bind('touchmove', function (e)
{
    alert("it worked but i don't know the direction");
});

But i don't know how to determine the direction.

Is this possible?

Or do i need to use touchstart/touchend, if I need this can I determine the direction before the touch movement stops?

If I can only do this with an external library, what's the best one?

thanks.