Should jQuery be used in "every" HTML/CSS/JavaScript application?

The answer is NO . When you use a library or framework, the question that comes to mind is:

Do I really need it?

Obviously, dozens of reasons go through your head and in the end, what motivates you to choose between one or the other are the needs you have. When jquery was born , the way to develop in JavaScript for cross-platform purposes was literally a nightmare, you had to take many things into account and make a code for each browser in most cases. It can be said that jquery was born as a polyfill for IE6.

Since that time things have changed a lot; the committee in charge of the specification started to work, the community started creating many better and better libraries and frameworks; New concepts such as Virtual DOM , reactive programming , data binding , etc. began to be popularized.

In my opinion, jquery for professional-scale modern web development is totally obsolete; some people will disagree, others will. I think that nowadays handling the DOM directly is no longer necessary; in fact, abusing this can reflect negatively on the performance of your application. With jquery you do this exhaustively because it was created for this and, if already manipulating the DOM too much can mean bad performance, using jQuery you reduce the ops/s brutally . Nowadays, new techniques have appeared that offer better solutions that are worth using. The evolution of a technology ecosystem always improves what already exists.

Is it necessary to use a library like jquery for my project?

The answer will depend on the scale of the project; for small projects, es6 and higher is enough and more than enough; for medium and large scale projects it is better to rely on an efficient framework that means less development effort/time and a more flexible development model.

Is jquery really the best option for what I need?

The answer can be answered with another question: Are there better alternatives that allow me to do the same thing in a more efficient and dynamic way ?

I think that using jquery also depends on the level of experience you have with javascript ; obviously for a purely backend programmer, using jquery will be much easier than using vue.js or reactjs with redux ; however, if we stick to an objective reality, it is better if, as far as possible, we use alternatives that mean greater productivity and provide us with greater benefits, such as code quality, efficiency, scalability, etc.

The truth is that frontend development has evolved considerably and new solutions to old problems have appeared , more efficient, more compact, more concise solutions; This is why frameworks have been born that are revolutionizing frontend development, such as reactjs or vue.js.

As they say in this world... Use the right tool for the right job .

There are several conflicts in use jQuerybetween them:

1. Unnecessary dependency "Do I really need jQuery?"

   If you're developing a library on the other hand, please take a moment to consider whether you really need jQuery as a dependency. Maybe you can include some useful lines of code, and forget about the dependency. If your focus is primarily modern browsers, you may not need anything other than what the browser offers.

2. Security, there are dozens of attacks using a fakejQuery

   Hackers use the popular jQuery Javascript library to inject malicious code into sites powered by WordPress and Joomla.

3. Performance, while it is true that jQuery is fast, code forking and feature detection result in penalties, not to mention wrappers about DOM2 features, where the stack trace is broader

   https://jsperf.com/jquery-vs-javascript-performance-comparison/22

4. Penalty in loading the page, if you use a stable and small version as it is jQuery 1.7, its minified version weighs only as 1Kibmuch as ! super mario bros weighed only ! 3 times less than ... those still need to be parsed and interpreted, resulting in a lag in page loadjQuery 3.087Kib31KibjQuery 3.087Kib

5. Extra Data Consumption (only for mobile devices) Mobile phones generally use planes de datosthose offered by telephone service companies, these planeshave a service charge , so when your page loads it jQuery 3.0is unnecessarily spending these resources, if the user uses a browser without a system of caché(absurd today, but imagine that there is one), for each page of your website, you would be spending 87Kib, that is to say that if your user enters and leaves the page a few 1024times he will have consumed 87 Mibonly loading jQuery...

6. extra learning curve

7. Sugary syntax, the sugary syntax of jQuerywith $(TODO)worsens the readability of the code, not to mention the absurd and excessive use of anonymous functions for everything.

In general, it's best NOT to use jQuery, and if you do use it, it's best to just extract the necessary modules

The bad thing about object-oriented programming is that if you want a banana, you bring the banana, the gorilla, and the whole jungle - Joe Armstrong

To complete the previous answers, I must add that today (April 2018), the popularity of other frameworks such as Angular, React, Vue... and tools such as Typescript, WebPack and Babel.js has meant that we do not need to access to the DOM in the classic way or that we don't have to worry about incompatibilities between different browsers and the W3C standard.

In fact, mixing Angular or React with jQuery is completely counterproductive because component lifecycles are handled in a very different way by these frameworks and the potential interference of jQuery only makes life difficult for any developer.

jQuery has gone from being THE library to being one more option in a world that is evolving at an enormous speed.