1/ HTML and CSS
Hyper Text Markup Language (HTML) and Cascading Style Sheets (CSS) are the basic building blocks of web coding. It is not possible to create a web page without these two languages. Prior to getting started on a web development career path, one of the first things you would have done is master coding with CSS and HTML. Front end developers are required to know these languages well.
3/ CSS Preprocessing
This skill is related to CSS. Although CSS is essential on its own, it can be limiting at times. An example of a limitation is the inability to define functions, variables or carry out arithmetic operations. Using a CSS preprocessor enables developers to write code in the language of the processor. This will allow you to do things that can be difficult with CSS alone.
4/ Version Control/Git
After hard work styling with CSS, making up with HTML and programming with JS, you will have gone through several divisions in your development. If anything goes wrong along the way, you will not want to start over from the beginning. Version control is the procedure for tracking and controlling changes in your source code. By using version control software such as open source stalwart Git, you can track the changes in order to go back to a previous version of your work and determine what went wrong without having to tear down the whole thing.
6/ Front End Frameworks
7/ Debugging/ Testing
Bugs occur during the development process of any website. In order to ensure that things keep moving, you must test your code for bugs during the development process. Therefore, the capability to test and debug is an essential skill to have as a front end developer.
8/ Automation and Building Tools/ Web performance
9/ Command line
The rapid increase of Graphic User Interfaces in computing is a great thing. It is much easier to point and click on an interactive, lively menu. GUIs are also alluring when it comes to coding and web development. However, an all purpose GUI can have limitations for various applications. There will be a time when you will find it necessary to open a terminal on your computer in order to enter typed commands (the command line) so that you can get what you need. Even though you can do most of your work through a graphic user interface, you will add significant credibility to your front end skills if you have mastered the command line.
Having worked with devs across a wide range of niches and technologies for quite some time now, I am hopeful I have included all those which are relevant, if there are any you feel are missing that are worthy of a mention, please get in touch.