Javascript 刷卡检测

我使用了以下代码来检测刷卡。它很好用

    function swipedetect(el, callback){

 var touchsurface = el,
 swipedir,
 startX,
 startY,
 distX,
 distY,
 threshold = 150, //required min distance traveled to be considered swipe
 restraint = 100, // maximum distance allowed at the same time in perpendicular direction
 allowedTime = 300, // maximum time allowed to travel that distance
 elapsedTime,
 startTime,
 handleswipe = callback || function(swipedir){}

 touchsurface.addEventListener('touchstart', function(e){
  var touchobj = e.changedTouches[0]
  swipedir = 'none'
  dist = 0
  startX = touchobj.pageX
  startY = touchobj.pageY
  startTime = new Date().getTime() // record time when finger first makes contact with surface
  e.preventDefault()

 }, false)

 touchsurface.addEventListener('touchmove', function(e){
  e.preventDefault() // prevent scrolling when inside DIV
 }, false)

 touchsurface.addEventListener('touchend', function(e){
  var touchobj = e.changedTouches[0]
  distX = touchobj.pageX - startX // get horizontal dist traveled by finger while in contact with surface
  distY = touchobj.pageY - startY // get vertical dist traveled by finger while in contact with surface
  elapsedTime = new Date().getTime() - startTime // get time elapsed
  if (elapsedTime <= allowedTime){ // first condition for awipe met
   if (Math.abs(distX) >= threshold && Math.abs(distY) <= restraint){ // 2nd condition for horizontal swipe met
    swipedir = (distX < 0)? 'left' : 'right' // if dist traveled is negative, it indicates left swipe
   }
   else if (Math.abs(distY) >= threshold && Math.abs(distX) <= restraint){ // 2nd condition for vertical swipe met
    swipedir = (distY < 0)? 'up' : 'down' // if dist traveled is negative, it indicates up swipe
   }
  }
  handleswipe(swipedir)
  e.preventDefault()
 }, false)
}

函数swipedetect（el，回调）{
var touchsurface=el，
瑞士人，
startX，
斯塔蒂，
distX，
迪西，
threshold=150，//考虑刷卡所需的最小移动距离
约束=100，//垂直方向上同时允许的最大距离
allowedTime=300，//允许移动该距离的最大时间
时光流逝，
开始的时候，
handleswipe=callback | |函数（swipider）{}
touchsurface.addEventListener（'touchstart'，函数（e）{
var touchobj=e.changedTouches[0]
swipedir=‘无’
距离=0
startX=touchobj.pageX
startY=touchobj.pageY
startTime=new Date（）.getTime（）//记录手指首次接触表面的时间
e、 预防默认值（）
}，错）
touchsurface.addEventListener（'touchmove'，函数（e）{
e、 preventDefault（）//在DIV内时防止滚动
}，错）
touchsurface.addEventListener（'touchend'，函数（e）{
var touchobj=e.changedTouches[0]
distX=touchobj.pageX-startX//获取手指在接触表面时移动的水平距离
distY=touchobj.pageY-startY//获取手指接触表面时移动的垂直距离
elapsedTime=new Date（）.getTime（）-startTime//获取经过的时间
如果（elapsedTime=threshold&&Math.abs（distY）=threshold&&Math.abs（distX）