此跨域ajax请求如何工作？

服务器正在响应，并将Access-Control-Allow-Origin设置为允许跨域请求

Response HeadersAccess-Control-Allow-Origin: *  Cache-Control   max-age=604800Connection  keep-aliveContent-Length  494Content-Type    application/json

http://www.w3.org/TR/cors/#access-control-allow-origin-response-
hea

http://hacks.mozilla.org/2009/07/cross-site-xmlhttprequest-with-
cors