swipe is left or right? about flexisel HOT 1 CLOSED

var touchHandler = {

    xDown: null,
    yDown: null,
    handleTouchStart: function(evt) {                                         
        this.xDown = evt.touches[0].clientX;                                      
        this.yDown = evt.touches[0].clientY;
    }, 
    handleTouchMove: function (evt) {
        if (!this.xDown || !this.yDown) {
            return;
        }

        var xUp = evt.touches[0].clientX;                                    
        var yUp = evt.touches[0].clientY;

        var xDiff = this.xDown - xUp;
        var yDiff = this.yDown - yUp;
        
        // only comparing xDiff
        // compare which is greater against yDiff to determine whether left/right or up/down  e.g. if (Math.abs( xDiff ) > Math.abs( yDiff ))
        if (Math.abs( xDiff ) > 0) {
            if ( xDiff > 0 ) {
                // swipe left
                console.log("left")
            } else {
                //swipe right
                console.log("right")
            }                       
        }
        
        /* reset values */
        this.xDown = null;
        this.yDown = null;
        canNavigate = true;
    }
}

document.getElementById("flexiselDemo1").addEventListener('touchstart', touchHandler.handleTouchStart, false);        
document.getElementById("flexiselDemo1").addEventListener('touchmove', touchHandler.handleTouchMove, false);