I have seen two structures. The first is that there is a static folder in the back-end project, which contains the packaged front-end code, and the other is that a server folder is added to the front-end folder, which is the back-end code. I am doing the front-end, which way is better if I want to do a nodejs (koa-2) background system. It is not very clear to remove these concepts for the first time, thank you