An application developer needs to know several computer languages if they're to create multiple applications. Generally, they should know at least one language to build computer programs. Sometimes, they need to learn a different language for the front-end and another one for the back-end.
Straightforward to Learn
Flexible Programming Language
If you prefer a shorter tutorial, Easy Essay suggests that you take this course from Programming with Mosh. It only lasts for an hour. You may take it if you only need a quick refresher or you're a fast learner. Josh is an experienced programmer offering a concise tutorial to at least two million subscribers on YouTube. His course covers the fundamentals, including loops, objects, functions, conditions, ES6 features, and arrays.
5. Intro to JS: Drawing & Animation