php 页面跳转

这样写可以正常跳转：

echo "<script>";
echo "window.location.href = '$url'";
echo "</script>";

而下面代码服务器返回空白页面，没有执行我的命令，请问是怎么回事？php小白，照葫芦画瓢写的代码：

echo "<script>";
echo "function()
{
   alert($error_msg);
   setTimeout(window.location.href = '$url',5);
}";                    
echo "</script>";
    

---

楼上仁兄正解

<?php
$url = "http://www.baidu.com";
$error_msg = "error";
echo "<script>";
echo "function jump()
{
   alert('$error_msg');
   window.location.href = '$url';
}
setTimeout(jump, 3000);
";                    
echo "</script>";

你js部分只是定义了函数没有调用啊

---

setTimeout(func,5);
前面func是一个方法

echo "<script>";
echo "function func()
{
   alert($error_msg);
   window.location.href = '$url';
}";
setTimeout(func,5);                    
echo "</script>";