移動端手指滑動距離

var startPosition={},deltaY,endPosition={};
document.addEventListener('touchstart',touch, false);  
document.addEventListener('touchmove',touch, false);  
document.addEventListener('touchend',touch, false);  
   
function touch (event){  
    var event = event || window.event;  
    switch(event.type){  
        case "touchstart":  
            var touch = event.touches[0];
		    startPosition = {
		        x: touch.pageX,
		        y: touch.pageY
		    }
            break;  
        case "touchend": 
　　　　　　　break;  
        case "touchmove":  
            var touch = event.touches[0];
		    endPosition = {
		        x: touch.pageX,
		        y: touch.pageY
		    }
	    deltaY = endPosition.y - startPosition.y;
　　　　　　　break;  
    }  
       
}