Everyday a great number of new people start to study programming and web development. The Front-end is one of the main areas of software development that are chosen by this people. And they have a lot of questions about what framework/library to learn, what tools to use and etc.
But, if I could give an advice to them, I would say that the most important thing is to dominate the fundamental technologies of the web. Become advanced in this technologies, not just learn the basic stuff, because with this solid fundamentals, the path to learn advanced librarys, frameworks and tools will be easier than before.
The three main Front-end technologies hide a trap. Its easy to learn the basics, but hard to learn the advanced concepts and know this advanced content will be the difference in your career as a developer.
This technologies use the 20-80 rule. With 20% of the effort you will learn 80% what you need to start to work in the market. The problem is that only know the basics will make you have a lot of issues in problem solving, taking you to difficulties, bugs and errors.
The big problem is that learn this other 20% requires 80% of the effort!
Template engines like liquid, pug, EJS and etc is converted to HTML.
The pre-processors like SASS and LESS is just CSS with some other features.
The learning curve to this hype tools is very low if you have an advanced knowledge in the fundamentals. Here is an amazing website with a list of the topics that is nice to learn in the three technologies and a lot of others too: Web Skills Website