🟢 Custom Eslint Rule

Information

ESLint is an amazing tool that helps developers avoid simple mistakes and adhere to company style guides.

In this first example, we will create a rule that forbids the use of enums. The rule will suggest using string unions instead of enums whenever an enum is present in this repo’s code. This is a straightforward rule for learning how to create rules.

You will also need to write tests to verify the rule’s functionality.

The starter code for this challenge can be found (from the root folder) inside tools/eslint-rules/rules.

To test the rule inside your project, add "@nx/workspace/forbidden-enum": "error" to the eslintrc.json. You can navigate to Challenge 47, `Enums vs. Union Types’, and you should immediately see an error.

To assist you with AST (Abstract Syntax Tree) definitions, you can visit the AST Explorer and use JavaScript, @typescript-eslint/parser, and ESLint-v8 as the transformation methods. However, please note that you will only get the type information there. The transformation function may not work for TypeScript types since the editor is in JavaScript.

You can also check this repo for ESLint rule examples.