ESLint configuration combining:

• functional programming.
• Standard JavaScript which prescribes how to format your code.
• Prettier which automatically formats your code as part of your build process or inside your IDE.
• editorconfig which fulfills a similar goal but more generic and limited.
• modularity by encouraging splitting your code into small modules and functions.
• modern JavaScript.
• strictness.

The configuration is very opinionated but you can override specific rules in your .eslintrc to fit your needs and coding style.

Install

$ npm install -D eslint-config-standard-prettier-fp [email protected]^6.3.0 [email protected]^6.2.0 [email protected]^14.1.0 [email protected]^0.3.2 [email protected]^8.0.0 [email protected]^3.1.2 [email protected]^1.3.2 [email protected]^2.3.0 [email protected]^6.0.0 [email protected]^2.18.2 [email protected]^1.0.0 [email protected]^10.0.0 [email protected]^4.2.1 [email protected]^4.0.1 [email protected]^10.0.0 [email protected]^6.7.0 [email protected]^1.18.2

Then add the following files.

.eslintrc.yml:

extends: standard-prettier-fp/.eslintrc.yml

.prettierrc.yml:

eslint-config-standard-prettier-fp

.gitattributes:

* text=auto eol=lf

Finally copy the .editorconfig:

$ cp node_modules/eslint-config-standard-prettier-fp/.editorconfig .

Prettier

prettier must be run before eslint to avoid conflicts.

We recommend using first prettier --write then eslint --fix --cache.

Do not forget to add .eslintcache to your .gitignore file.

Coding style

Functional programming

State should be immutable.

Variables and object properties should be read-only. They should be copied instead of mutated. Assignment should only happen during declaration.

The following patterns should be avoided as they imply state:

• loops (for, while). Use functional methods (like Array.map() and Array.filter()) and recursion instead.
• classes/OOP. To inherit/share behavior, use composition or generic programming instead.
• events. Use promises and streams instead.

Global variables should not be used except the ones that are built-in (e.g. Object).

Throwing exceptions is allowed as this can simplify code.

Modularity

Code should be split into small files and functions:

• files have at most 90 non-empty lines and 10 dependencies.
• functions have at most 4 branches and 10 statements.
• branches/blocks should not be nested.
• lines are at most 80 characters long.

Modern JavaScript

• ES modules. Exports should be named (no export default).
• object and array destructuring.
• object spreading: { ...object } instead of Object.assign({}, ...object)
• arguments spreading: funcName(...args) instead of funcName.call(this, ...args)
• parameters spreading: function(...args) instead of function(arguments)
• template strings instead of concatenation.
• async/await instead of explicit promises or callbacks.
• vanilla JavaScript instead of Lodash/Underscore.
• only JavaScript features supported by the Node.js version specified in your package.json engines field.

Strictness

The configuration is very explicit and enforces strict linting. This should help you find bugs and maintain a consistent coding style:

• no dead code.
• typecasting should be explicit.
• file dependencies should be sorted.
• variable names should remain short.
• constants should be assigned to variables.
• avoiding turning off ESLint rules with comments.
• RegExps should use the u flag.
• no variables shadowing.

Other styling rules

• named parameters (i.e. passing an object as single parameter) instead of positional parameters.
• function declarations should be const funcName = function() { ... }

HTML and Markdown

eslint-plugin-html and eslint-plugin-markdown are included so you can lint JavaScript inside HTML or Markdown files.

Support

If you found a bug or would like a new feature, don't hesitate to submit an issue on GitHub.

For other questions, feel free to chat with us on Gitter.

Everyone is welcome regardless of personal background. We enforce a Code of conduct in order to promote a positive and inclusive environment.

Contributing

This project was made with ❤️. The simplest way to give back is by starring and sharing it online.

If the documentation is unclear or has a typo, please click on the page's Edit button (pencil icon) and suggest a correction.

If you would like to help us fix a bug or add a new feature, please check our guidelines. Pull requests are welcome!

ehmicky 💻 🎨 🤔 📖