'use strict'; const _ = require('lodash'); const config = require('../../config/common'); const dnsPrefetch = require('../../config/dns-prefetch'); module.exports = () => { return (req, res, next) => { if (_.get(req.app.locals, 'pc.qcloud_cdn')) { res.locals.cdn = 'qcloud'; } else { res.locals.cdn = config.cdn || 'aliyun'; } let cdn = []; if (res.locals.cdn === 'qcloud') { cdn = _.uniq(_.values(dnsPrefetch)); } else { cdn = Object.keys(dnsPrefetch); } Object.assign(res.locals, { dnsPrefetch: cdn }); next(); }; };