ESLint Config Best Practices for Angular Projects

eslint.config.js

// @ts-check
const eslint = require('@eslint/js');
const tseslint = require('typescript-eslint');
const angular = require('angular-eslint');
const eslintConfigPrettier = require('eslint-config-prettier');

module.exports = tseslint.config(
  {
    ignores: ['.angular/**', '.nx/**', 'coverage/**', 'dist/**'],
    files: ['**/*.ts'],
    extends: [
      eslint.configs.recommended,
      ...tseslint.configs.recommended,
      ...tseslint.configs.stylistic,
      ...angular.configs.tsRecommended,
      eslintConfigPrettier,
    ],
    processor: angular.processInlineTemplates,
    rules: {
      '@angular-eslint/directive-selector': [
        'error',
        {
          type: 'attribute',
          prefix: 'app',
          style: 'camelCase',
        },
      ],
      '@angular-eslint/component-selector': [
        'error',
        {
          type: ['attribute', 'element'],
          prefix: 'app',
          style: 'kebab-case',
        },
      ],
      // Angular best practices
      '@angular-eslint/no-empty-lifecycle-method': 'warn',
      '@angular-eslint/prefer-on-push-component-change-detection': 'off', // should be turned on!
      '@angular-eslint/prefer-output-readonly': 'warn',
      '@angular-eslint/prefer-signals': 'warn',
      '@angular-eslint/prefer-standalone': 'warn',
      // TypeScript best practices
      '@typescript-eslint/array-type': ['warn'],
      '@typescript-eslint/consistent-indexed-object-style': 'off',
      '@typescript-eslint/consistent-type-assertions': 'warn',
      '@typescript-eslint/consistent-type-definitions': ['warn', 'type'],
      '@typescript-eslint/explicit-function-return-type': 'error',
      '@typescript-eslint/explicit-member-accessibility': [
        'error',
        {
          accessibility: 'no-public',
        },
      ],
      '@typescript-eslint/naming-convention': [
        'warn',
        {
          selector: 'variable',
          format: ['camelCase', 'UPPER_CASE', 'PascalCase'],
        },
      ],
      '@typescript-eslint/no-empty-function': 'warn',
      '@typescript-eslint/no-empty-interface': 'error',
      '@typescript-eslint/no-explicit-any': 'warn',
      '@typescript-eslint/no-inferrable-types': 'warn',
      '@typescript-eslint/no-shadow': 'warn',
      '@typescript-eslint/no-unused-vars': 'warn',
      // JavaScript best practices
      eqeqeq: 'error',
      complexity: ['error', 20],
      curly: 'error',
      'guard-for-in': 'error',
      'max-classes-per-file': ['error', 1],
      'max-len': [
        'warn',
        {
          code: 120,
          comments: 160,
        },
      ],
      'max-lines': ['error', 400],
      'no-bitwise': 'error',
      'no-console': 'off',
      'no-new-wrappers': 'error',
      'no-useless-concat': 'error',
      'no-var': 'error',
      'no-restricted-syntax': 'off',
      'no-shadow': 'error',
      'one-var': ['error', 'never'],
      'prefer-arrow-callback': 'error',
      'prefer-const': 'error',
      'sort-imports': [
        'error',
        {
          ignoreCase: true,
          ignoreDeclarationSort: true,
          allowSeparatedGroups: true,
        },
      ],
      // Security
      'no-eval': 'error',
      'no-implied-eval': 'error',
    },
  },
  {
    files: ['**/*.html'],
    extends: [...angular.configs.templateRecommended, ...angular.configs.templateAccessibility],
    rules: {
      // Angular template best practices
      '@angular-eslint/template/attributes-order': [
        'error',
        {
          // alphabetical: true,
          order: [
            'STRUCTURAL_DIRECTIVE', // deprecated, use @if and @for instead
            'TEMPLATE_REFERENCE', // e.g. `<input #inputRef>`
            'ATTRIBUTE_BINDING', // e.g. `<input required>`, `id="3"`
            'INPUT_BINDING', // e.g. `[id]="3"`, `[attr.colspan]="colspan"`,
            'TWO_WAY_BINDING', // e.g. `[(id)]="id"`,
            'OUTPUT_BINDING', // e.g. `(idChange)="handleChange()"`,
          ],
        },
      ],
      '@angular-eslint/template/button-has-type': 'warn',
      '@angular-eslint/template/cyclomatic-complexity': ['warn', { maxComplexity: 10 }],
      '@angular-eslint/template/eqeqeq': 'error',
      '@angular-eslint/template/prefer-control-flow': 'error',
      '@angular-eslint/template/prefer-ngsrc': 'warn',
      '@angular-eslint/template/prefer-self-closing-tags': 'warn',
      '@angular-eslint/template/use-track-by-function': 'warn',
    },
  },
);