var timerlen = 5;
var slideAniLen = 1000;
var timerID = [];
var startTime = [];
var obj = [];
var endHeight = [];
var moving = [];
var dir = [];

function startslide(objname){
  obj[objname] = document.getElementById(objname);
 
  endHeight[objname] = parseInt(obj[objname].style.height, 10);
  startTime[objname] = (new Date()).getTime();
 
  if(dir[objname] == "down"){
    obj[objname].style.height = "1px";
  }
 
  obj[objname].style.display = "block";
 
  timerID[objname] = setInterval('slidetick(\'' + objname + '\');',timerlen);
}

function slidedown(objname){

  if(moving[objname]) {
    return;
  }

  if(document.getElementById(objname).style.display != "none") {
    return; // cannot slide down something that is already visible
  }
 
  moving[objname] = true;
  dir[objname] = "down";
  startslide(objname);
}
 
function slideup(objname){
  if(moving[objname]) {
    return;
  }
 
  if(document.getElementById(objname).style.display == "none") {
    return; // cannot slide up something that is already hidden
  }
 
  moving[objname] = true;
  dir[objname] = "up";
  startslide(objname);
}


function endSlide(objname){
  clearInterval(timerID[objname]);
 
  if(dir[objname] == "up") {
    obj[objname].style.display = "none";
  }
 
  obj[objname].style.height = endHeight[objname] + "px";
 
  delete(moving[objname]);
  delete(timerID[objname]);
  delete(startTime[objname]);
  delete(endHeight[objname]);
  delete(obj[objname]);
  delete(dir[objname]);
 
  return;
}

function slidetick(objname){
  var elapsed = (new Date()).getTime() - startTime[objname];
 
  if (elapsed > slideAniLen) {
    endSlide(objname);
  } else {
    var d =Math.round(elapsed / slideAniLen * endHeight[objname]);
    if(dir[objname] == "up"){
      d = endHeight[objname] - d;
    }
 
    obj[objname].style.height = d + "px";
  }
 
  return;
}