Nodejs’ Front and Rear End Separation Scheme

  node.js, question

How to use nodejs to separate front and back ends?
In the system I have developed at present, nodejs is responsible for the back-end logical API, business routing, and rendering the routing relationship between the front-end and front-end of the web.
As a result, everything revolved around nodejs, not separation at all.
What should be the front-end and rear-end separation scheme of the excellent nodejs?

 Now, aren't many people advocating using nodejs and other backend to render the front end to improve loading efficiency?
 If you just do the front-end and back-end separation, all the requests will be done with AJAX, but the problem of efficiency comes up again.
 If the front pages are all made into templates (I use ejs), the coupling degree between the front and back ends is too high.
 I don't know how to deal with this problem and whether there is a formed plan. After all, I am relatively junior and can't handle this kind of problem well.
 Because the concepts of nodejs plus front-end and back-end separation plus full stack are quite popular
 Just wondering if I can use nodejs knowledge to try something new.
 It is better to manage the framework of cross-platform projects such as webapp in the future.
 (once and for all?  !  )

Taobao UED’s plan actually regards Node as part of the big front end.