const Koa = require('koa');
const app = new Koa()
//public是指的放置前端静态资源的文件夹名称
app.use(require('koa-static')(__dirname + '/public'))
app.listen(3000)

Vue打包完部署到服务器运行(express、koa)
https://blog.csdn.net/balloonhunter/article/details/106595739