预解析的实现：
注：dns-prefetch需慎用，多页面重复DNS预解析会增加重复DNS查询次数。
代码示例：
<meta name="viewport" content="width=device-width,initial-scale=1,minimum-scale=1,maximum-scale=1,user-scalable=no">
<meta http-equiv="x-dns-prefetch-control" content="on" />
<link rel="dns-prefetch" href="https://unpkg.com" />
<link rel="dns-prefetch" href="https://cdn.jsdelivr.net" />
<link rel="stylesheet" href="https://unpkg.com/element-ui/lib/theme-chalk/index.css">
原文：http://www.cnblogs.com/zifayin/p/7831512.html