We describe having these sets of skills as being a "front-end" developer. You use three languages to create pages inside a web browser like Safari, Firefox, Edge or Chrome. Given how popular the web is for commerce and information sharing, there is a massive demand for people who are good at using these three languages.
Related to the role of being a "front-end" developer is the set of skills for the "back-end" developers, which are to create computer services that communicate either to a web browser (by passing it HTML/CSS/JS) or to another service (by sending data more directly.) You don't need to use HTML, CSS or JS to write this type of code, but it's usually an end-product of your work because it is likely to be presented in a web browser.
Traditional Creative Director, Software Engineer and Tech Writer