eslint-config-rocket

"Enterprise Grade Linting"

Philosophy

When coding at scale ensuring high quality code as a project ages can prove difficult. Linting can drastically improve code quality by front loading many of the issues that should be caught in code review to the point where a developer has the most context.

Eslint is a really powerful tool that can do a lot, but there are some things it is better at than others. These configurations aim to focus on what it is good at. Namely improving code quality by making patterns more consistent and encouraging the use of modern language features.

Special Cases

The goal isn't to prevent patterns from being used, but instead to encourage good patterns by default and documenting where patterns need to be broken via required descriptions on disable directives.

If for example I needed to use let for some reason I could do so with the following directive.

// eslint-disable-next-line prefer-const -- This needs to be let
let something = '';

Requiring descriptions like this not only encourages thought about why this pattern is being broken by the developer but by the entire team during code review and future developers coming back to add to and refactor this code.

Having clear descriptions on when linting rules are broken also transparently teaches developers new to the code base what is and is not common practice within the organization

Single Warning Policy

With how powerful eslint is there is a lot of overlap between it and other tools. These configurations intentionally disable any rules that overlap with the functions of a tool that does a better job at enforcing that particular rule.

With how many rules there are across the wide range of plugins this configuration uses there are many that may overlap with each other. Where ever possible these configurations attempt to pick a single rule of those that overlap so that any given problem is only reported once.

Code Formatting

Code formatting is extremely useful when working on a team as it as it reduces the number of changes that aren't meaningful leaving only the important parts for code review. Additionally having consistent formatting makes code much easier to read and switch contexts in the code base.

But, linting works best when it is showing you meaningful warnings and potentially unexpected behavior. Code Formatting rules just increase the noise which which makes more important warnings seem less important.

As such these configurations do not include any code formatting (quote style, indenting, spacing, etc.) rules. There are much better tools out there (prettier) for code formatting so I would encourage you to use those and enable format on save before you consider overriding the eslint configurations with code formatting rules.

Type Checking

Writing JavaScript without Type Checking is like playing web dev on hardcore mode. It is so easy to shoot yourself, or your friend, in the foot. We have many great tools now that luckily make our lives much easier. Chief among them is TypeScript. While ESLint can enforce many type rules, TypeScript does a far better job so any rules that overlap with options or checking already done in TypeScript are intentionally disabled much like code formatting rules and I would encourage you to explore your tsconfig.json options before looking to enable any of those rules.

Usage

1. Install the configuration

   npm install -D eslint-config-rocket

2. Add a .eslintrc.js to the root of your project that looks something like this

   module.exports = {
     overrides: [
       {
         extends: [
           'rocket/typescript',
           'rocket/angular',
           'rocket/rxjs',
           'rocket/ngrx',
         ],
         files: '**/*.ts',
         excludedFiles: ['**/*.md.ts', '**/*.spec.ts'],
         parserOptions: { project: './tsconfig.json' },
       },
       {
         extends: ['rocket/typescript', 'rocket/jest'],
         files: '**/*.spec.ts',
         parserOptions: { project: './tsconfig.json' },
         settings: { jest: { version: 26 } },
       },
       {
         extends: ['rocket/angular-template'],
         files: '**/*.html',
         parserOptions: { project: './tsconfig.json' },
       },
       {
         extends: ['rocket/javascript', 'rocket/node'],
         files: '**/*.js',
         excludedFiles: '**/*.md.js',
       },
       {
         extends: ['rocket/markdown'],
         files: ['*.md'],
       },
       {
         extends: [
           'rocket/javascript',
           'rocket/node',
           'rocket/markdown-snippet',
         ],
         files: '*.md.js',
       },
       {
         extends: [
           'rocket/javascript',
           'rocket/angular',
           'rocket/ngneat',
           'rocket/rxjs',
           'rocket/ngrx',
           'rocket/markdown-snippet',
         ],
         files: '*.md.ts',
       },
     ],
     root: true,
   };

   Note: TypeScript rules are not available available in Markdown because while eslint knows how to parse markdown, TypeScript still doesn't.

   You can adjust the configuration to the needs of your project. You may also consider making a configuration for each package if you are using a monorepo to apply the proper platform configurations where they are applicable.

Generator

If you are using an nx workspace you can use the eslint-config-rocket:config to configure your project the the correct eslint extensions.

nx generate eslint-config-rocket:config [projectName] [options,...]

Options:
  --projectName           The name of the project to configure (see workspace.json)
  --language              Wether to use JavaScript or TypeScript
  --framework             The framework this project was written with
  --testing               The testing framework the project uses
  --libraries             A list of libraries that this project consumes

Entry Points

Overview

Each of your extends should consist of either a platform, framework and one or more libraries OR a other-parser.

['<platform>', '<framework>', ...libraries];
// OR
['<other-parser>'];

The supported entry points are

Platforms

• rocket/javascript
• rocket/typescript

Frameworks

• rocket/angular
• rocket/node
• rocket/react
• rocket/react-native

Testing Frameworks

• rocket/cypress
• rocket/jest

Utils

• rocket/lodash
• rocket/markdown-snippet
• rocket/ngneat
• rocket/ngrx
• rocket/rxjs
• rocket/storybook

Other Parsers

• rocket/angular-template
• rocket/markdown

Rules Overriding

Depending on your project, you may choose to override or add additional rules. To do this simply add a rules with any rules you wish to override under the specific overrides where the rule applies.

Mono repo import sorting

If you wish to sort your can add this rule to your configuration replacing <your-organization> with the namespace of your packages.

{
  "extends": ["rocket/import-order"]
  "rules": {
    "import/order": [
      "warn",
      {
            "alphabetize": {
              "order": "asc",
              "caseInsensitive": false
            },
            "groups": [["external", "builtin"], "internal", "parent", "sibling"],
            "newlines-between": "always",
            "pathGroups": [
              {
                "group": "sibling",
                "pattern": "./*-routing.module",
                "position": "before"
              },
              {
                "group": "external",
                "pattern": "{@<your-organization>/**,}",
                "position": "before"
              },
              {
                "group": "external",
                "pattern": "{@rx-angular/**,@ngrx/**,react-*,@vue/**}",
                "position": "before"
              },
              {
                "group": "external",
                "pattern": "{@angular/**,@nativescript/**,@nestjs/**,react,react-native,vue,@ngneat/spectator,@ngneat/spectator/**}",
                "position": "before"
              }
            ],
            "pathGroupsExcludedImportTypes": ["react"]
      }
    ]
  }
}

Credits

The project structure and original rule set that has been customized and further expanded upon and been provided by eslint-config-intense