Programming

In that case, my suggestion would be to target implementing a REST API with OpenAPI (formerly Swagger). There are server code generators for both Rust and JS (multiple flavors, I think).

Basically, the workflow is something like this:

1. Create your API spec skeleton (YAML or JSON, pick your poison). This will have all of the required sections like info
2. Pick your first endpoint and define it in the paths section. Probably start with during simple like a GET. This will mean that you mainly have to worry about defining your responses (at minimum HTTP2XX and HTTP4XX, preferably with a catchall error response for HTTP5XX responses) and their schemas.
3. Run the code generator. This should generate files with stubbed-out definitions for interfaces (or the equivalent for your language of choice) for your response methods. Generally, you do NOT want to add any code to these files as they will be overwritten anytime you update your API spec.
4. Implement the methods to handle the stubbed out interfaces. Ex. A hello-world interface would likely need to be implemented with a method or function that returns the string "hello world".

The reason that I recommend OpenAPI in writing REST APIs is that it helps to layout the API contracts before you even start coding. This helps with keeping typing consistent, give you a clear milestone for implement, and makes creating clients really easy.

Extra benefit is that OpenAPI is (mostly) language agnostic, so, as long as you have a codegen or some good boilerplate, you can use it for any language, which can give you a safe place to start when learning a new language.