function $(id) {
 return document.getElementById(id);
}

function scrollBanner(timer, moveNumber) {
 
 function move(o) {
  var st = document.documentElement.scrollTop + o.t;
  var sl = document.documentElement.scrollLeft + (o.c == 0 ? o.a : document.documentElement.clientWidth - o.a - o.offsetWidth);
  var tc = st - o.offsetTop, lc = sl - o.offsetLeft;
  with (o.style) {
   top = o.offsetTop + (tc != 0 ? tc / Math.abs(tc) : 0) * Math.min(Math.abs(tc), moveNumber) + "px";
   left = o.offsetLeft + (lc != 0 ? lc / Math.abs(lc) : 0) * Math.min(Math.abs(lc), moveNumber) + "px";
  }
  if (o.person) {
   with (o.person.style) {
    top = o.offsetTop + "px";
    left = o.offsetLeft + o.offsetWidth - o.person.offsetWidth + "px";
   }
  }
 }
 
 var hidden = function() {
  var o = this.parent;
  window.clearInterval(o.interval);
  o.parentNode.removeChild(o);
  this.parentNode.removeChild(this);
 }
 
 this.add = function (to, t, a, c, lo) {
  /*
  to为object对象
  t为距离顶端距离
  当c = 0的时候，a为距离左边的距离
  当c != 0的时候，a为距离右边的距离
  lo为关闭按钮
  */
  var div, exec = function () {
   move(to);
  };
  
  to.person = lo;
  to.t = t;
  to.a = a;
  to.c = c;
  with (to.style) {
   position = "absolute";
   display = "block";
   top = document.documentElement.scrollTop + t;
   left = document.documentElement.scrollLeft + (c == 0 ? a : document.documentElement.clientWidth - a - to.offsetWidth);
  }
  
  if ("undefined" != typeof lo) {
   with (lo.style) {
    position = "absolute";
    display = "block";
   }   
   lo.onmousedown = hidden;
   lo.parent = to;
  }
  exec();
  to.interval = window.setInterval(exec, timer);
 };
}

window.onload = function () {
 var b = new scrollBanner(10, 10);
 b.add($("lwc"), 50, 10, 0);
 b.add($("rwc"), 50, 10, 1, $("rwc_c"));
 b = null;
}