function getCoords(event) {
      // touch move and touch end have different touch data
      var touches = event.touches,
          data = touches && touches.length ? touches : event.changedTouches;

      return {
        x: isTouch ? data[0].pageX : event.pageX,
        y: isTouch ? data[0].pageY : event.pageY
      };
    }
Returns an object containing the co-ordinates for the event, normalising for touch / non-touch.
@param {Object} event
@returns {Object}