var stopscroll=false;
 var preTop=0; 
 //var newTop=0;
 var currentTop=0; 
 var stoptime=0;
 var iInterval ;

 function init_srolltext(){
 document.body.scrollTop=0;
 document.body.onmouseover   = new Function("stopscroll=true");
 document.body.onmouseout    = new Function("stopscroll=false");
 document.body.oncontextmenu = new Function("return false;");
 document.body.onselectstart = new Function("return false;");
 iInterval = setInterval("scrollUp()",10);
 }

 function scrollUp(){
  if(stopscroll==true) return;
  currentTop+=1; //每次滚动 1 个象素
  if(currentTop==47){ //刚滚动完一行后(每行高23)
   stoptime+=1;  //停顿时间累计 1 个单位时间(10毫秒)
   currentTop-=1; //滚动位移数恢复原值
   if(stoptime==100){ //停顿时间累计 100 个单位时间后重新计算滚动位移和停顿时间
    currentTop=0;
    stoptime=0;
    //if(confirm("One line end ...... \n\nok to stop , cancel to go on.")){clearInterval(iInterval);}
   }
  }else{   
   document.body.scrollTop = preTop +1; //滚动 1 个象素
   if(preTop< document.body.scrollTop){
    preTop = document.body.scrollTop ;
   }
   else {//如果滚动到末尾了(滚动跟没滚一样)
    preTop = 1
    document.body.scrollTop = 1;
    //if(confirm("scroll to all text ending.......["+preTop+"/"+document.body.scrollTop+"] \n\nok to stop , cancel to go on.")){clearInterval(iInterval);}
   }
  }
 }
 
 init_srolltext(); //启动