Tools like babel and eslint works based on plugin architecture, under the hood they use ASTs to explore the program and make correcctions or transformations. Also adventages using this approach instead of Regular Explressions

We explore how a program is translated to AST using AST Explorer, the different parsers to create AST what tools use them and how works Visitor Pattern to make modifications on the source code

For demo I make a eslint plugin with rules to avoid import "dangerous packages"