I disagree with this.
TypeScript is currently high in demand (as you see) due to it being currently being used heavily in the industry for web development. However, that doesn’t mean its the best investment of the limited funds freeCodeCamp has. The main reason is because TypeScript is just an extension of JavaScript, where both are just being tools for web development.
Move beyond the environment of web development, and TypeScript/JavaScript knowledge starts becoming less and less useful. Let alone other web specific technologies like HTML/CSS, which is almost 100% domain knowledge. Web is a popular domain, but it isn’t the only domain.
This doesn’t apply to concepts that are focused on with the mathematics based curriculum. Math doesn’t go out of style. Regardless of language, environment, technology your using, its the same.
Furthermore, as noted in the article these topics are actually not taught very often in any platform beyond colleges. Making it “ripe” for learning. Especially as the “main weakness” of curriculum’s like freeCodeCamp is usually the lack of focus on the underlying theory. FCC already teaches a lot of practical skills, it doesn’t teach everything, but it does go over a lot. However, few online curriculum’s focus on the hard Computer Science topics underpinning a lot of what your learning.
It could be argued that “time and effort be spent on topic X, could be spent on topic Y”, but I find it really hard to say a technology, even one like TypeScript, is more important than the underlying theory. Yea your resume might look better, but understanding theory is what makes you be able to do your job better.
PS. I use Angular+TypeScript daily. If your strong at JavaScript, TypeScript will follow. Focused learning starting with TypeScript is how you get more confused with the underlying language, so I don’t recommend it, using freeCodeCamp or not. There is nothing stopping you from doing the projects using TS either. FCC just wont be able to help you, in which case the actual TS docs should be the main source, the same way you shouldn’t rely only on fCC to learn React/Redux/Node.js/jQuery/SASS. FCC is just the starting point, not the be-all-end-all.