What micro js/css libraries/frameworks would you recommend for learning?

Question

css

Little by little I am learning web programming "for myself" in the hope of implementing my own project (that is, not for teamwork, this is essential). In terms of the backend, I chose microframeworks like Slim or FatFree. Now I want to find similar solutions for the frontend. That is, that it was not a huge monster, but something small, simple and concise.
Unlike php, there is such an abundance in the javascript world that it will make your eyes run wide ...
For css, Bootstrap is usually mentioned. Due to the lack of any experience at all, I can’t judge whether it is good or bad, but perhaps if there are some more lightweight alternatives, it will be interesting to get acquainted.
For js, they usually mention a lot of things, on Habré there are enumerations with dozens (!) Of different frameworks and libraries. Angular, React, Vue.js and dozens more titles. It’s generally difficult here, so I’ll just give the criteria for what I need to start.
1. Easy to learn
2. Minimalistic; no super bells and whistles are needed, I am my own artist and task manager, and it would be better if the library provides some simple, visually clean solutions for the most common tasks, and not a set of everything for all occasions.
3. Lightness; the site should not slow down on weak or crap-loaded users' machines
4. Better a library than a framework, in the sense that the library provides more freedom, and the framework usually requires that the code be written in accordance with its framework, rules and architecture.
5. Many people now surf the Internet through mobile devices ... I don’t know how to develop a mobile version of the site or one universal version. The first option seems more logical to me, because for mobile devices not only the screen size is smaller, but also the control is different. But, in general, this also somehow needs to be taken into account ...

Answer 1

Easy to learn... Minimalist; no super bells and whistles... will provide some simple, visually clean solutions to the most commonly encountered problems... Lightweight... provides more freedom...

For starters, you should try the good old VanillaJS - it just suits your requirements.
PS: Do not take this as humor, given that
you will also not be able to evaluate the good or bad of any other tool that will be mentioned in the answers to this question, and the only way that will lead you to a meaningful choice is to study the basics.

Answer 2

there are conceptual ones, there are instrumental (utilitarian) ones.
conceptual frameworks are needed mainly for developing some kind of real applications for clients (in a browser, for example). they force you to follow a certain logic of building the code and the entire system as a whole. the benefit here is that any other developer of about the same level will quickly figure it out. angular for example conceptual. but you can’t just write anything there, you need to learn how to work on it. those. the entry threshold is higher than in instrumental ones.
instrumental or utilitarian frameworks are more like a set of screwdrivers, pliers and files. You don't have to "specially" use them. the sole purpose of their existence is to ensure the uniform execution of certain simple actions or to make "shortcuts" (abbreviations) of long codes into short understandable commands. the simplest example is jquery. just a collection of useful utility functions that do their job well and provide a consistent interface.
therefore, often the main conceptual (complex) frameworks become simpler, instrumental frameworks.

Answer 3

Perhaps React falls under your criteria.
It is a library,
individual modules can be loaded separately "as needed",
with proper directness of hands, nothing will slow down.
The only negative is a little "unusual" in the study, but knowing es6, there should be no problems.

Answer 4

I have a feeling you are learning from the wrong place.
js to learn from a framework? php as well?
In my opinion, on the contrary, language -> framework. Moreover, starting to understand any language - not a lib or an engine in this language - namely the language, such questions will disappear. Other languages ​​are more quickly mastered, an understanding comes of why it is better to use one / another language and the lib / engine based on it.
You will have enough sorts / comments / docs / if you're lucky - high-quality examples to understand how it is done in this language / engine / lib, and why, and even how to improve.
Zero start - basic language basics, syntax, operators, etc. Example for js: https://learn.javascript.ru/
UPD:
Then or in parallel, try to write your undescore.js with an eye to undescore itself)
First, there will be a large js file with almost copy-paste, you see - when you get to the promises - there will be a project on the gita not in the form of a single file, but wrapped in webpack + testem + little things with sorts in es6 and spoilers)