Why do we need such js libraries?

Question

css

I recently learned about js libraries such as vue.js and react.js , when I started looking at what they can do, I did not quite understand their meaning. After reading about them, I saw that their main advantage over jquery is reactivity, but they are essentially a frontend, and I can easily write all the animations I need in css , interaction with them can be implemented in js / jquery, and there will not be much confusing code and brakes. All conclusions can also be drawn through markup, since in any case it will have to be written into the code (because js does not work with db). A logical question arises - is it worth spending time studying such libraries, which, if they give a gain in reactivity, are almost imperceptible, if I didn’t understand something, then explain, maybe I really missed something.

Answer 1

You have a lot of information in your head mixed up in a continuous mess.
First of all, understand the terminology, and then a lot will fall into place.
Frontend is the common name for the whole complex of site development works: html/css/js.
Vue.js, React.js and the like are not libraries (unlike jQuery), but web frameworks.
(upd: I was corrected in the comments that React is still a library)
A library is generally a set of tools that simplify some type of task, these tools can be used and combined as you like.
frameworkis a much more complex structure. the main difference from the library is that you are given some foundation within which you need to implement tasks.
The advantage of libraries is that your hands are free, you are not limited by any structure, and in general you are a free artist. The downside is that as soon as you need to implement something more complicated than animations and multiple event handlers, the code very quickly becomes confusing and hard to refactor.
Accordingly, the advantages of using frameworks are the possibility of much simpler scaling of applications, the minus is a higher entry threshold: you won’t be able to use the entire available arsenal out of the heat of the day.
Using a web framework relieves you of the need to create the foundation and structure of a web application yourself (if you carefully read the documentation, of course - you can stick crutches with any tool).
The choice of what to work with depends on the level and complexity of your goals and tasks.

Answer 2

for a large project, definitely, on a small one you may not understand the pros