JavaScript操作CSS樣式實現簡單的驗證碼的功能：
注意：這裏只是樣式與驗證碼相似，但真正的驗證碼是用圖片做的；
<!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>
<script type="text/javascript">
//產生4位的驗證碼
function createCode(){
var datas = ['A','B','C','1','2','3','5','6','楊','張','任'];
var code = "";
for(var i=0 ; i < 4 ; i++){
var index = Math.floor(Math.random()*datas.length);
code += datas[index];
}
var spanNode = document.getElementById("code");
spanNode.innerHTML = code;
spanNode.style.fontSize="24px";
spanNode.style.color="red";
spanNode.style.backgroundColor="gray";
spanNode.style.textDecoration="line-through";
}
function ready(){
createCode();
}
</script>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>JavaScript操作CSS樣式</title>
</head>
<body οnlοad="ready()">
<span id="code"></span><a href="#" οnclick="createCode()">看不清，換一個</a>
</body>
</html>