ESLint Plugin Custom Angular

A custom ESLint plugin that extends @angular-eslint/eslint-plugin@19.3.0 with additional fixes, and suggestions for Angular applications.

🚀 Features

• Enhanced Angular Rules: Custom rules built on top of @angular-eslint
• Automatic Fixes: Many rules include automatic code fixes
• Smart Suggestions: Intelligent suggestions for code improvements
• TypeScript Support: Full TypeScript support with proper type checking

📦 Installation

npm install eslint-plugin-custom-angular --save-dev

🔧 Configuration

Add the plugin to your ESLint configuration:

// eslint.config.js
const eslint = require("@eslint/js");
const tseslint = require("typescript-eslint");
const custom = require("eslint-plugin-custom-angular");

module.exports = tseslint.config({
  files: [ "**/*.ts" ],
  plugins: { "custom-angular": custom },
  extends: [ eslint.configs.recommended, ...tseslint.configs.recommended ],
  rules: {
    // Enable all rules
    "custom-angular/component-max-inline-declarations": "error",
    "custom-angular/no-duplicates-in-metadata-arrays": "error",
    "custom-angular/relative-url-prefix": "error",
    "custom-angular/sort-lifecycle-methods": "error"
  }
});

📋 Available Rules

component-max-inline-declarations

Enforces a maximum number of lines in inline animations. Automatically extracts long inline declarations to separate variables. If reuse the array destructuring it into inline animations array will have suggestions.

Options:

• animations (number): Maximum lines allowed for animations (default: 15)

Example:

// ❌ Too many lines
@Component({
  animations: [
    trigger('dialogContainer', [
      transition('* => void', query('@transformPanel', [animateChild()], {optional: true}))
    ]),
    // ... more animations
  ]
})

// ✅ Automatically fixed to
const myAnimations: unknown[] = [
  trigger('dialogContainer', [
    transition('* => void', query('@transformPanel', [animateChild()], {optional: true}))
  ]),
  // ... more animations
];

@Component({
  animations: myAnimations
})

no-duplicates-in-metadata-arrays

Ensures that metadata arrays do not contain duplicate entries. Automatically removes duplicates.

Example:

// ❌ Duplicate entries
@NgModule({
  imports: [CommonModule, CommonModule, RouterModule],
  declarations: [AppComponent, AppComponent]
})

// ✅ Automatically fixed to
@NgModule({
  imports: [CommonModule, RouterModule],
  declarations: [AppComponent]
})

relative-url-prefix

Enforces the use of ./ and ../ prefixes for relative URLs in Angular components.

Example:

// ❌ Missing relative prefix
@Component({
  templateUrl: 'app.component.html',
  styleUrls: ['app.component.css']
})

// ✅ Automatically fixed to
@Component({
  templateUrl: './app.component.html',
  styleUrls: ['./app.component.css']
})

sort-lifecycle-methods

Ensures that lifecycle methods are declared in order of execution. Automatically reorders methods.

Example:

// ❌ Incorrect order
export class AppComponent {
  ngOnInit() { }
  constructor() { }
  ngOnDestroy() { }
}

// ✅ Automatically fixed to
export class AppComponent {
  constructor() { }
  ngOnInit() { }
  ngOnDestroy() { }
}

Available Scripts

• npm run build - Build the plugin
• npm run tests - Run all tests with coverage
• npm run serve-coverage - Serve coverage report locally
• npm run deploy - Build and publish to npm

Testing

Run tests for all rules:

npm run tests

Coverage

[!warning] python3 is required

View coverage report:

npm run serve-coverage

Then open http://localhost:8000 in your browser.

🤝 Acknowledgments

• Built on top of @angular-eslint
• Inspired by Angular's official style guide
• Developed as part of a Final Degree Project (TFG)