关于document.domain 和cookie跨域

Question

如下如图，我想在二级域名之间实现cookie的跨域，但是以下代码无法实现，请问下各位大佬，我哪里写错了啊？？
hosts：

127.0.0.1       cross1.cross.com
127.0.0.1       cross2.cross.com

nginx：

#...省略
server{
        listen 80;
        server_name cross1.cross.com;  
        location / {
            root e:\/cross1;
            index index.html;
        }
    }
    server{
        listen 80;
        server_name cross2.cross.com;  
        location / {
            root e:\/cross2;
            index index.html;
        }
    }
#...省略

cross1/index.html

<script>
    document.domain ='cross.com';
    document.cookie="name=value";
</script>

cross2/index.html

<script>
    document.domain ='cross.com';
    console.log(document.cookie,'cross2');
</script>

这是cross1.html的cookie

这是cross2.html的打印，可以看到没有任何显示，就是无法获取到cross1/index.html设置的cookie啊，这个是咋回事呀？

Answer 1

var cookieName = 'HelloWorld';
var cookieValue = 'HelloWorld';
var myDate = new Date();
myDate.setMonth(myDate.getMonth() + 12);
document.cookie = cookieName +"=" + cookieValue + ";expires=" + myDate 
                  + ";domain=.example.com;path=/";