use nuxt as a middleware to provide different views according to user-agent

nuxt_pc_mobile.js

const app = express();
app.use(router);

const configPC = require('../pc/nuxt.config.js');
const configSP = require('../sp/nuxt.config.js');
const nuxtPC = new Nuxt(configPC);
const nuxtSP = new Nuxt(configSP);

// Enable live build & reloading on dev
if (nuxtPC.options.dev) {
    new Builder(nuxtPC).build()
}

if (nuxtSP.options.dev) {
    new Builder(nuxtSP).build()
}

app.use((req, res, next) => {
    const md = new MobileDetect(req.headers['user-agent']);
    if (md.mobile()) {
        nuxtSP.render(req, res);
    } else {
        nuxtPC.render(req, res);
    }
});