Frage

<script language="JavaScript1.2">
<!--

var snowsrc="gfxu/snow.gif"
var no = 10;
var ns4up = (document.layers) ? 1 : 0; 
var ie4up = (document.all) ? 1 : 0;
var dx, xp, yp;   
var am, stx, sty;
var i, doc_width = 1024, doc_height = 768;
if (ns4up) {
    doc_width = self.innerWidth;
    doc_height = self.innerHeight;
  } else if (ie4up) {
    doc_width = document.body.clientWidth;
    doc_height = document.body.clientHeight;
  }

  dx = new Array();
  xp = new Array();
  yp = new Array();
  am = new Array();
  stx = new Array();
  sty = new Array();
 
  for (i = 0; i < no; ++ i) { 
    dx[i] = 0;                       
    xp[i] = Math.random()*(doc_width-50); 
    yp[i] = Math.random()*doc_height;
    am[i] = Math.random()*20;         
    stx[i] = 0.02 + Math.random()/10;
    sty[i] = 0.7 + Math.random();     
    if (ns4up) {                     
      if (i == 0) {
        document.write("<layer name=\"dot"+ i +"\" left=\"15\" top=\"15\" visibility=\"show\"><a href=\"http://www.jswelt.de/\"><img src='"+snowsrc+"' border=\"0\"></a></layer>");
      } else {
        document.write("<layer name=\"dot"+ i +"\" left=\"15\" top=\"15\" visibility=\"show\"><img src='"+snowsrc+"' border=\"0\"></layer>");
      }
    } else if (ie4up) {
      if (i == 0) {
        document.write("<div id=\"dot"+ i +"\" style=\"POSITION: absolute; Z-INDEX: "+ i +"; VISIBILITY: visible; TOP: 15px; LEFT: 15px;\"><a href=\"http://java.topcool.de\"><img src='"+snowsrc+"' border=\"0\"></a></div>");
      } else {
        document.write("<div id=\"dot"+ i +"\" style=\"POSITION: absolute; Z-INDEX: "+ i +"; VISIBILITY: visible; TOP: 15px; LEFT: 15px;\"><img src='"+snowsrc+"' border=\"0\"></div>");
      }
    }
  }
   function snowNS() { 
    for (i = 0; i < no; ++ i) { 
      yp[i] += sty[i];
      if (yp[i] > doc_height-50) {
        xp[i] = Math.random()*(doc_width-am[i]-30);
        yp[i] = 0;
        stx[i] = 0.02 + Math.random()/10;
        sty[i] = 0.7 + Math.random();
        doc_width = self.innerWidth;
        doc_height = self.innerHeight;
      }
      dx[i] += stx[i];
      document.layers["dot"+i].top = yp[i];
      document.layers["dot"+i].left = xp[i] + am[i]*Math.sin(dx[i]);
    }
    setTimeout("snowNS()", 10);
  }
  function snowIE() { 
    for (i = 0; i < no; ++ i) { 
      yp[i] += sty[i];
      if (yp[i] > doc_height-50) {
        xp[i] = Math.random()*(doc_width-am[i]-30);
        yp[i] = 0;
        stx[i] = 0.02 + Math.random()/10;
        sty[i] = 0.7 + Math.random();
        doc_width = document.body.clientWidth;
        doc_height = document.body.clientHeight;
      }
      dx[i] += stx[i];
      document.all["dot"+i].style.pixelTop = yp[i];
      document.all["dot"+i].style.pixelLeft = xp[i] + am[i]*Math.sin(dx[i]);
    }
    setTimeout("snowIE()", 10);
  }

  if (ns4up) {
    snowNS();
  } else if (ie4up) {
    snowIE();
  }
// -->
</script>