javascript - 如何使用 Javascript 使 div 可滚动

I am working on Tizen and making web app.

我有一个 html5 的 div，我将图像设置为该 div 的背景。现在我有一些场景，我必须在这个 div 中多次显示一些随机文本。不能保证文本始终具有相同的大小。我的图像尺寸是 300 宽和 90 高。

现在，每当我的文本较大时，我想通过 javascript 设置我的 div 向上和向下滚动。我尝试了scrollTop，overflow:auto/scroll，但它不起作用。

实际上，我可以在 Eclipse 中的 HTML View 上看到结果，但是当我在设备上运行代码时，它没有显示任何滚动条。任何帮助将不胜感激。

Here is my code in which I have a div named textView:

  <div id="textView" style="height: 90px; width: 300px;  
    margin-left: 20px; margin-top: 20px;overflow: auto;">
  </div>

And in javascript:

  var elem = document.getElementById("textView");

  elem.scrollTop="80px";

  elem.innerHTML="llllllllllllllllllllllllllllllllllllllllll"+'<br/>'
  +"llllllllllllllllllllllllllllllllllllllllllll"+'<br/>'
  +"llllllllllllllllllllllllllllllllllllllllllll"+'</br>'
  +"llllllllllllllllllllllllllllllllllllllllllll"+'<br/>';
  elem.style.color = "White";

  elem.style.fontSize = "50px";