移動端touch滑屏事件

<script>    var windowHeight = $(window).height(),            $body = $("body");//     console.log($(window).height());//     console.log($('body').height());    $body.css("height", windowHeight);//    console.log($('body').height());    $("body").on("touchstart", function(e) {        e.preventDefault();        startX = e.originalEvent.changedTouches[0].pageX,                startY = e.originalEvent.changedTouches[0].pageY;    });    $("body").on("touchmove", function(e) {        e.preventDefault();        moveEndX = e.originalEvent.changedTouches[0].pageX,                moveEndY = e.originalEvent.changedTouches[0].pageY,                X = moveEndX - startX,                Y = moveEndY - startY;        if ( Math.abs(X) > Math.abs(Y) && X > 10 ) {            alert("left 2 right");        }        else if ( Math.abs(X) > Math.abs(Y) && X < 10 ) {            alert("right 2 left");        }        else if ( Math.abs(Y) > Math.abs(X) && Y > 10) {            alert("top 2 bottom");        }        else if ( Math.abs(Y) > Math.abs(X) && Y < 10 ) {            alert("bottom 2 top");        }        else{            alert("just touch");        }    });</script>