JavaScript cross-Domain access solution

Because of security considerations, JavaScript is limited to cross-domain access, but sometimes we want to be able to do some reasonable cross-domain access things, so what to do?

There are two types of situations:

One, access to the page between subdomains based on the same parent domain

See the following 3 domain domains:

1、taobao.com
　　 2、jipiao.taobao.com
　　 3、promotion.taobao.com

They have the same parent domain taobao.com

Second, based on the access between different parent domain pages

See the following 3 domain domains:

1、taobao.com
　　 2、baidu.com

3, sina.com.cn

They have different parent domains.

Scenarios for resolving cross-domain between them:

<!--[if!supportlists]-->①<!--[endif]--> Server proxy: Domain A's page JS needs access to the link under Domain B to obtain data, which establishes a proxy program on the server side of Domain A ( May be ASP, servlet, and so on any server-side program, domain A page JS directly call this domain proxy program, proxy program is responsible for the request sent to the link under the domain B and get the data, and finally through proxy to return the data to the page JS use.

After the access process is: Domain A under the Js--à domain A proxy---à domain B under the link

Example:

First step:

JavaScript script on domain a:http://jipiao.taobao.com/test.htm page

<script type=”text/javascript”>
　 Var sUrl=” http://Jipiao.taobao.com/proxy.do”; //本域下代理地址
var callback =
{
　 success: function(res) { alert(res.responseText); },
　 failure: function(res) {　alert(‘failure’);},
　 argument:{}
}
　 YAHOO.util.Connect.asyncRequest(’GET’, sUrl, callback, null);
</script>