Linter Configuration

This guide describes the recommended linter configuration for Node.js projects (back/front) + CloudFormation.

Prerequisites

The following dependencies needs to be installed manually:

Install Docker Desktop
Install Node.js 22.x
Upgrade NPM to the most recent version:
```
$ npm install --global npm@latest
```
Install Python 3.x
Install CloudFormation linter:
```
$ pip install cfn-lint
```

$ pip install cloudformation-cli cloudformation-cli-python-plugin

Upgrade the above Python packages periodically by running:

$ pip install --upgrade cfn-lint cloudformation-cli cloudformation-cli-python-plugin

CFN Lint Plugins

There are IDE plugins available to get direct linter feedback from you favorite editor:

Atom
Emacs
NeoVim 0.2.0+/Vim 8
- ALE
- Coc
- Syntastic
SublimeText
Visual Studio Code
IntelliJ IDEA

EditorConfig Plugins

EditorConfig helps maintain consistent coding styles for multiple developers working on the same project across various editors and IDEs.

EditorConfig Backend Config

Copy the following configuration to your .editorconfig file:

root = true

[*]

# Change these settings to your own preference
indent_style = space
indent_size = 4

# We recommend you to keep these unchanged
end_of_line = lf
charset = utf-8
trim_trailing_whitespace = true
insert_final_newline = true

[*.md]
trim_trailing_whitespace = false

[*.{json,xml,yml,yaml}]
indent_size = 2

EditorConfig Frontend Config

Copy the following configuration to your .editorconfig file:

root = true

[*]

# Change these settings to your own preference
indent_style = space
indent_size = 2

# We recommend you to keep these unchanged
end_of_line = lf
charset = utf-8
trim_trailing_whitespace = true
insert_final_newline = true

[*.md]
trim_trailing_whitespace = false

Eslint Backend Config

Install NPM dependencies:

npm install --save-dev \
    @eslint/js \
    eslint-plugin-eslint-comments \
    eslint-plugin-json \
    eslint-plugin-mocha \
    eslint-plugin-promise \
    eslint-plugin-yml \
    globals

Copy the following configuration to your eslint.config.js file:

import js from '@eslint/js';
import globals from 'globals';
import eslintYml from 'eslint-plugin-yml';
import eslintJson from 'eslint-plugin-json';
import eslintMocha from 'eslint-plugin-mocha';
import eslintComments from 'eslint-plugin-eslint-comments';

export default [
    js.configs.recommended,

    {
        languageOptions: {
            ecmaVersion: 2022,
            sourceType: 'module',
            globals: {
                ...globals.node,
                document: true,
            },
            parserOptions: {
                sourceType: 'module',
                ecmaVersion: 'latest',
            },
        },
        plugins: {
            yml: eslintYml,
            json: eslintJson,
            mocha: eslintMocha,
            'eslint-comments': eslintComments,
        },
        rules: {
            semi: 'error',
            curly: 'error',
            strict: ['error', 'safe'],
            eqeqeq: 'error',
            indent: ['error', 4, { SwitchCase: 1 }],
            quotes: ['error', 'single', { avoidEscape: true }],
            camelcase: ['error', { properties: 'never' }],
            'array-bracket-spacing': ['error', 'never'],
            'arrow-spacing': 'error',
            'comma-dangle': ['error', 'always-multiline'],
            'eol-last': 'error',
            'func-call-spacing': 'error',
            'max-depth': ['error', 3],
            'max-len': ['error', { code: 100 }],
            'max-nested-callbacks': ['error', 3],
            'max-statements-per-line': ['error', { max: 1 }],
            'newline-per-chained-call': ['error', { ignoreChainWithDepth: 3 }],
            'no-duplicate-imports': 'error',
            'no-multi-assign': 'error',
            'no-multiple-empty-lines': ['error', { max: 1, maxEOF: 0 }],
            'no-nested-ternary': 'error',
            'no-trailing-spaces': 'error',
            'no-unneeded-ternary': 'error',
            'no-useless-constructor': 'error',
            'no-var': 'error',
            'object-curly-spacing': ['error', 'always'],
            'prefer-const': 'error',
            'space-before-blocks': 'error',
            'brace-style': 'error',
            'keyword-spacing': 'error',
            'space-before-function-paren': ['error', {
                named: 'never',
                anonymous: 'never',
                asyncArrow: 'always',
            }],
            'spaced-comment': ['error', 'always'],
            'no-whitespace-before-property': 'error',
            'arrow-parens': ['error', 'always'],

            // plugin:yml rules
            'yml/quotes': ['error', {
                prefer: 'single',
                avoidEscape: true,
            }],

            // plugin:eslint-comments rules
            'eslint-comments/no-use': 'error',
        },

        ignores: [
            'node_modules/**',
            'coverage/**',
            '.aws-sam/**',
            '.next/**',
            '.dist/**',
            'dist/**',
            'out/**',
            '!.github/**',
        ],
    },

    // Test files configuration
    {
        files: ['test/**/*'],
        languageOptions: {
            globals: {
                describe: 'readonly',
                it: 'readonly',
                before: 'readonly',
                after: 'readonly',
                beforeEach: 'readonly',
                afterEach: 'readonly',
            },
        },
        rules: {
            'max-nested-callbacks': ['error', 10],
            'mocha/no-mocha-arrows': 'off',
            'mocha/no-skipped-tests': 'error',
            'mocha/no-exclusive-tests': 'error',
        },
    },
];

Eslint Frontend Config