Input文本框随着输入内容多少自动延伸

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>无标题文档</title>
<script language="javascript">
function checkLength(which) {
    var oTextCount = document.getElementById("char");
    iCount = which.value.replace(/[^/u0000-/u00ff]/g,"aa");
    oTextCount.innerHTML = "<font color=#FF0000>"+ iCount.length+"</font>";
    which.style.border = '1px dotted #FF0000';
which.size=iCount.length+2;
}
</script>
</head>
<body>
<input name="words" size="2"    onkeyup="checkLength(this)"/>
    <span id="char">0</span>个字符
</body>
</html>
http://www.corange.cn/archives/2008/01/111.html