I will say that technologies that can replace JavaScript in browsers have only recently appeared. Still, it will take a long time before they reach a sufficient level of development and learn all that JavaScript can do. And in the server and embedded systems, JavaScript has a lot of alternatives, but it's a niche there too. Many companies have invested, and continue to support, a lot of money in developing engines that run JavaScript and that make the language more and more effective and relevant. The demand on the job market for JavaScript developers dramatically exceeds the supply, hence the good salaries. Companies are now looking for developers of any level, including beginners. https://ithire.com/category/react-developers