对于div内的js,window.location.href无效,而window.open有效

为什么放入div中的submit按钮触发的onclick的js中window.location.href = "http://www.baidu.com";无效,而window.open("http://www.qq.com", "_blank");有效呢?我想网页重定向,应该怎么改呢?
以下是HTML代码:

 <!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>跳转</title>
</head>

<script type="text/javascript">
    function jstiaozhuan() {
        window.location.href = "http://www.baidu.com";
        window.open("http://www.qq.com", "_blank");
    }
</script>

<body>
<div id="formContainer">
    <form id ="aa" method="ttt">
    <input type="submit" name="submit" value="跳转" onclick="jstiaozhuan()" value="sign">
    </form>
</div>
</body>

</html>

window.location.href= "http://www.baidu.com" 无效是因为跨域的问题。所以只能用window.open或者用iframe

要return false阻止表单的提交,要么type="submit" 改为type="button"

 <!DOCTYPE html>
<html>
<head>
    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
    <title>跳转</title>
</head>

<script type="text/javascript">
    function jstiaozhuan() {
        window.location.href = "http://www.baidu.com";
        //window.open("http://www.qq.com", "_blank");
        return false
    }
</script>

<body>
    <div id="formContainer">
        <form id="aa" method="ttt">
            <input type="submit" name="submit" value="跳转" onclick="return jstiaozhuan();" value="sign">
        </form>
    </div>
</body>

</html>