完美运动框架

function startMove(obj, json, fn)
{
 clearInterval(obj.timer);
 obj.timer=setInterval(function (){
  var bStop=true;  //这一次运动就结束了——所有的值都到达了
  for(var attr in json)
  {
   //1.取当前的值
   var iCur=0;
   
   if(attr=='opacity')
   {
    iCur=parseInt(parseFloat(getStyle(obj, attr))*100);
   }
   else
   {
    iCur=parseInt(getStyle(obj, attr));
   }
   
   //2.算速度
   var iSpeed=(json[attr]-iCur)/8;
   iSpeed=iSpeed>0?Math.ceil(iSpeed):Math.floor(iSpeed);
   
   //3.检测停止
   if(iCur!=json[attr])
   {
    bStop=false;
   }
   
   if(attr=='opacity')
   {
    obj.style.filter='alpha(opacity:'+(iCur+iSpeed)+')';
    obj.style.opacity=(iCur+iSpeed)/100;
   }
   else
   {
    obj.style[attr]=iCur+iSpeed+'px';
   }
  }
  
  if(bStop)
  {
   clearInterval(obj.timer);
   
   if(fn)
   {
    fn();
   }
  }
 }, 30)
}