This is a simple example of a babel-macros macro.
You'll notice that the input.js file is importing the ./greeting.macro.js file
Then the imported identifiers are used throughout the code. The macro itself
is about as simple as you can get with a babel-macros macro. It accepts the
references to those imports and replaces the references with string literals.
Take a look at the output.js file to see what the result is. Now mess around
with it a bit to see what you can do with this thing!
Hopefully this helps you get started trying out writing a macro!
Writing a macro is similar to writing a babel-plugin except you give up a little power in favor of a simpler setup for you and the user of your macro (maybe also you). Because it's so similar to writing a babel-plugin, it could be really helpful to learn how to write babel-plugins and using ASTs. Here are some resources for that:
- babel-plugin-handbook
- Writing custom Babel and ESLint plugins with ASTs
- Code Transformation and Linting with Abstract Syntax Trees
From there, you may also want to reference the babel-macros docs
Good luck!