How are websites built on React and Next?

Question

React

Please tell me if I am making a site on React.js or Next.js.
Layout is done immediately in React components? Or is the classic layout done first, and then transferred to React? And the second question is if the site is on React, should everything be on React, or is it allowed to make some elements on native Js without React?

Answer 1

Layout is done immediately in React components? Or is the classic layout done first, and then transferred to React?

As you prefer.
You can order layout on outsourcing, and then transfer it to React. And you can immediately typeset on react components.
If I make some component that is complex in terms of layout, I first simply layout it in pure HTML, then decompose it into subcomponents, if this is the case, and then add reactivity and conditional rendering logic. I think this way the component turns out to be better, in terms of layout.

if the site is on React, everything must be on React or it is allowed to make some elements on native Js

React by its very nature is a library that can be added to any site.
Which means that you can have 90% static layout and 10% on react (some kind of widgets, separate blocks or complex forms).
And vice versa.
Like 100% on react.