Everybody that works on websites probably has their browser open all day, but front-end developers live in there. They have DevTools open. They have multiple browsers open and test across versions and platforms. Crucially, they care about the users that interact with those browsers and assistive technology.It is not that back-end developers don’t care about users, it’s just that responsibility is delegated.

There are a lot of tools involved, but ultimately it comes down to HTML, CSS, and JavaScript. Whatever other tooling you use, it all comes down to what ships to the browser, and front-end developers are responsible for that.

Not all front-end developers know all the languages equally well. In fact, there are lots of developers out there who hardly write any JavaScript at all, but who are otherwise very successful front-end developers. And there are also a lot of front-end developers who write almost nothing but JavaScript.

In my opinion there are two kind of front-end developers and it's a weakness, but a strength in putting those different people together. Ones are " Front of the Front" and others "Back of the Front". There is not doubt that JavaScript went and got BIG. Particularly since about 2015 it has exploded as a language.

Front-end developers starting to do more full-stack work and having that role grow wider and wider, let’s just assume we’re talking about front-end developers who go down the heavier JavaScript road.

Over the last few years, we’ve started to see a significant shift in the role of the front-end developer. As applications have become increasingly JavaScript-heavy there has been a necessity for front-end engineers to understand and practice architectural principles that were traditionally in the domain of back-end developers, such as API design and data modeling.

Some people don't understand that a JavaScript developer is not per se a front-end developer. A JavaScript developer may not like to write CSS or care about semantics. That’s the same way I prefer not to work directly with databases or configure a server. That’s okay. What is not okay is if you don’t want to use something and at the same time tell others what they do is easy or useless. Even worse is if you try to tell experts in their field that they are doing it all wrong and that they should do it your way.

Robin Rendle says: "Maybe the term front-end developer needs some rethinking. When I started working, front-end was mostly HTML, CSS, and some JavaScript. A good front-end developer needed to be able to translate a Photoshop layout to a pixel perfect website. Front end today is much much more. If you want to learn front-end development, people seem to start learning git, npm, angular, react, vue and all of this is called front-end development. I am a designer and I think I’m pretty good at HTML and CSS, but that’s not enough anymore to be a front-end developer."

All the very huge responsibilities front-end developers already have:

• Pulling of the design
• Making the design part of a system
• Making sure it is accessible
• Worrying about the performance
• Testing things across browsers
• Testing things across devices
• Sweating the UX

Oh hello, big pile of new responsibilities

• Component-driven design, designing our own abstractions
• Site-level architecture
• Routing
• Fetching our own data
• Talking to APIs
• Mutating data
• State management