源码如下
var obj = event.currentTarget;
var left = parseInt(obj.style['margin-left']);
console.log("0>left>-500:"+(0>left>-500)+",,left:"+left);
if(0 > left > -500){
var nowX = event.originalEvent.touches[0].clientX||event.originalEvent.clientX ;
var number = nowX - this._x;
var newLeft = left + number;
obj.style['margin-left'] = newLeft + "px";
this._x = nowX;
}