server.js

const fs = require('fs')
const path = require('path')
const express = require('express')
const serialize = require('serialize-javascript')
const isTest = process.env.NODE_ENV === 'test' || !!process.env.VITE_TEST_BUILD

async function createServer(
    root = process.cwd(),
    isProd = process.env.NODE_ENV === 'production',
) {
    const resolve = (p) => path.resolve(__dirname, p)

    const indexProd = isProd
        ? fs.readFileSync(resolve('dist/client/index.html'), 'utf-8')
        : ''

    const manifest = isProd
        ? // @ts-ignore
        require('./dist/client/ssr-manifest.json')
        : {}

    const app = express()

    /**
     * @type {import('vite').ViteDevServer}
     */
    let vite
    if (!isProd) {
        vite = await require('vite').createServer({
            root,
            logLevel: isTest ? 'error' : 'info',
            server: {
                middlewareMode: 'ssr',
                watch: {
                    usePolling: true,
                    interval: 100,
                },
            },
        })
        app.use(vite.middlewares)
    } else {
        app.use(require('compression')())
        app.use(
            require('serve-static')(resolve('dist/client'), {
                index: false,
            }),
        )
    }

    app.use('*', async (req, res) => {
        try {
            const url = req.originalUrl
            let template, render
            if (!isProd) {
                template = fs.readFileSync(resolve('index.html'), 'utf-8')
                template = await vite.transformIndexHtml(url, template)
                render = (await vite.ssrLoadModule('/src/entry-server.js')).render
            } else {
                template = indexProd
                render = require('./dist/server/entry-server.js').render
            }

            const [appHtml, preloadLinks, headTags, store] = await render(url, manifest)

            const html = template
                .replace(`<!--preload-links-->`, preloadLinks)
                .replace(`<!--app-html-->`, appHtml)
                .replace(`<!--head-tags-->`, headTags)
                .replace(`'<vuex-state>'`, serialize(store.state))

            res.status(200).set({'Content-Type': 'text/html'}).end(html)
        } catch (e) {
            vite && vite.ssrFixStacktrace(e)
            console.log(e.stack)
            res.status(500).end(e.stack)
        }
    })

    return {app, vite}
}

if (!isTest) {
    createServer().then(({app}) =>
        app.listen(3000, () => {
            console.log('http://localhost:3000')
        }),
    )
}

exports.createServer = createServer