1. The koa in the project you generate with vue-cli is only useful in the development environment, and the simulation of server, does not require koa
2 in the production environment. Generally speaking, projects with separation of front and rear ends rarely need to add a layer of node, between front-end and back-end java, that is, koa, unless, like Taobao, it needs to be optimized on the first screen or has strong seo requirements, and what needs to be requested by the browser is a static page that can be displayed directly, or the api provided by the back-end java cannot be directly displayed to the front end, and needs to be transformed. In order to need node middle layer
3.vue-router is front-end routing, is executed in the browser, url changes, switching different pages, while koa-router is mainly aimed at the server, for api routing

Koa is the same thing as express library, that is, a web service . It seems that it is rare to get data in Koa , and then render static html . After all, getting data is a time-consuming process. Now the usual practice is to load html, first and then request data asynchronously.