In other words, can serious apps be built with just plain old jQuery?
React have obscure structure. I can't force myself to write HTML tags in a string of javascript files, rather than better use jQuery. If I wanna update my skills, I would choose Vue.js.
However, many websites are also using jQuery or non-javascript. Not necessarily apply the web components.
I'm still using it, I really want to use react, but it seems jQuery is really easy to pickup for beginners in my team.
My last job only used vanilla javascript and jquery.
Many projects are unfortunately still made in jQuery, so in that sense it can be nececssary to use.
jQuery was once made during browser wars, when different browsers implemented DOM selectors in different ways. Today, all major browsers use the official standards and the standards include functions to query the DOM. That's why jQuery is nothing more than bloat today (32KB of bloat, to be precise!).
const $ = document.querySelector;
const ele = $('div.user-panel.main input[name=login]');
ele.value = 'Hello World';
Further reading:
Ankit Singh
I work in a small startup whose web platform is written in Grails. The UI consist of two frameworks: Angular and GSP (Groovy Server Pages). While it's possible to use jQuery in GSP via a plugin, it's not possible to force use React or Angular in GSP. So yeah, if you are in a situation like this and working on a legacy system, you may want to use jQuery, even in 2017 because using it would be far more easier than reinventing the wheel.
If you are starting fresh on a personal project or in a startup, it's better to use Angular (good if it's Angular 1) or React. I've used all of them and personally, I like React. The JSX (html in JavaScript) may feel awkward at first most of it is like writing html with minor modifications. It's easier to write and look more beautiful than all the #hashes and $dollars in JQuery.