在静态资源的HTTP标头中设置过期日期或最长期限，指示浏览器从本地磁盘而不是通过网络加载以前下载的资源。
https://www.google.com/…oad=vcRecaptchaApiLoaded&render=explicit (5 minutes)
https://connect.facebook.net/en_US/sdk.js (20 minutes)
https://maps.googleapis.com/…=AIzaSyAy-BBHE1s92AY--7dxjbKCY5ZoLtUh7po (30 minutes)
https://www.google.com/jsapi (60 minutes)
https://www.google-analytics.com/analytics.js (2 hours)