Angular Code Review Checklist: All Steps Included

We all strive to build high-quality, maintainable, and secure applications. Whether you’re preparing a feature-packed release or scaling your product for a broader audience, thorough Angular code reviews are critical. Why? Because they help uncover hidden issues, maintain a uniform code style, and keep your development flow on track.

In this article, we’ll cover:

Why Code Review Matters for Angular

Angular has a modular structure powered by TypeScript, which already eliminates many of the headaches you’d get in regular JavaScript. Even with this extra help, it doesn’t mean you can skip code reviews. One stray “any”, an overlooked security gap, or some clumsy architecture could create big trouble. A thorough review will help you:

Keep your code consistent and easy to navigate
Spot performance drains before they spike your server bill
Tighten up security, especially around user-generated inputs
Promote a predictable flow of data and logic

If you’re seeking even more tips on why code reviews matter, you should check out our other checklists for Python, JavaScript, and Security.

Clear Project Architecture

A well-structured Angular project leads to fewer merge conflicts and a smoother onboarding experience for new developers. By separating features into modules, deciding which ones load lazily, and keeping file names logical, you set the stage for easy maintenance & scalability.

Feature Modules:

Group related functionalities under dedicated feature modules to prevent bloat in your main module and keep your code discoverable
Use shared modules for directives and components needed by multiple features
Monitor your routing configurations to see where lazy loading can boost performance

// Naive routing: everything is loaded at once, which makes the final bundle bigger
const routes: Routes = [
  { path: 'dashboard', component: DashboardComponent },
  { path: 'profile', component: ProfileComponent },
  // ...
];

// With lazy loading, only fetch modules on demand
const routes: Routes = [
  {
    path: 'dashboard',
    loadChildren: () => import('./dashboard/dashboard.module')
      .then(m => m.DashboardModule)
  },
  {
    path: 'profile',
    loadChildren: () => import('./profile/profile.module')
      .then(m => m.ProfileModule)
  }
];

Logical Folder Organization:

Give each folder a clear purpose (components, services, pipes, etc.) to avoid burying files in random locations
Name folders to match their functionality (e.g., users, products, reports), not with abstract terms like misc or general

Proper Versioning & CI/CD:

Tag releases in Git and automate your build checks. This ensures that new code merges correctly and that any architectural changes are tested early
Identify potential conflicts fast with a simple CI pipeline running ng build –prod along with lint checks

Consistent Coding Conventions

Styling rules might initially seem cosmetic, but a consistent style boosts productivity. Tools like Angular ESLint and Prettier automate most of the work, while a standard naming scheme keeps your app uniform.

Unified Lint & Format Rules:

Agree on a style guide (e.g., Angular Style Guide) so devs don’t waste time on cosmetic changes
Automate fixes with Prettier or ESLint. You can even run them as a pre-commit hook to keep the repo clean. Look through this short example of ESLint config, which can be easily extended with dozens of plugins and custom rules:

{
  "root": true,
  "overrides": [
    {
      "files": [
        "*.ts"
      ],
      "parserOptions": {
        "project": [
          "tsconfig.json",
          "e2e/tsconfig.json"
        ],
        "createDefaultProgram": true
      },
      // Can add ready-to-go config of Airbnb or others styleguides
      "extends": [
        "eslint:recommended",
        "plugin:@typescript-eslint/recommended",
        "plugin:@angular-eslint/recommended",
        "plugin:@angular-eslint/template/process-inline-templates"
      ],
      "rules": {
        // ...
      }
  }]
}

Meaningful Names:

Use descriptive variables and function names and avoid short placeholders like val or tmp.Angular favors clarity
Apply consistent naming to classes, files, and directories. For instance, user-profile.component.ts or auth.service.ts signals intent better than data.component.ts or logic.service.ts

Readable Functions:

Keep methods short and purposeful. If you’re tackling multiple tasks in one function, break it into logical parts
The same goes for entire classes—when a service starts doubling as a utility library, it’s time to split it up

Strict Typing & TypeScript Usage

One of Angular’s strong suits is TypeScript, which catches errors early and makes your data flow explicit. Overusing “any” negates those benefits and turns debugging into guesswork.

Leverage Interfaces:

Define data structures so you know exactly what’s coming in and out of your functions
If you’re returning user info, create a User interface for it

Here’s a quick example of how typing goes wrong without proper definition:

// Bad practice: using `any` everywhere, there is spelling error, which is not catched
function submitForm(event: any): any {
  event.preventDefaulr(); // runtime error!
  // ...
  return fetch(`https://api.example.com/users/${id}`)
    .then(res => res.json());
}


// Good practice: using interfaces gives ability to avoid common errors and easily access properties
function submitForm(event: MouseEvent | Keyboard): any {
  event.preventDefault();
  const isShiftKeyPressed = event.shiftKey;
  // ...
  return fetch(`https://api.example.com/users/${id}`)
    .then(res => res.json());
}

Use Strict Mode:

Enable “strict” in your tsconfig.json to simplify catching subtle typing errors. This is one of the fastest ways to boost your code’s reliability

Generics Where Appropriate:

Use generic classes or methods only if it’s necessary; avoid overcomplicated simple types

// Bad practice: Not constraining generics 
class BadDataService {
    process(data: T): T {
        return data; // No type safety or validation
    }
}

// Good practice: Using type inference and constraints
function transformAndValidate>(
    input: T,
    transform: (data: T) => R,
    validator: (data: R) => boolean
): R | null {
    const transformed = transform(input);
    return validator(transformed) ? transformed : null;
}

Lean Components & Templates

Angular’s component-driven structure makes it easy to split up your UI, but large components can still become cumbersome. Spread business logic into services and clean templates of heavy loops or calculations.

Lifecycle Hooks Done Right:

Only implement the hooks that you truly need. Unused hooks add clutter and confusion. For example, unsubscribe from observables in ngOnDestroy() if you’re manually subscribing
Don’t forget to use the correct interface in the component

Limit Template Logic:

A template swamped with nested loops and conditions is difficult to debug. To solve this, move repeated transformations into a pipe or method in the component class
Keep your HTML readable by wisely leveraging Angular directives like ngIf and ngFor

Refactor Overgrown Components:

If a single component has grown to hundreds of lines, it’s time to split it up
To keep your main component focused, shift data processing to a service or sub-component

Effective Dependency Injection

Dependency injection is a hallmark of Angular, but it’s easy to misuse. Too many providers at the root level will bloat your app, and singletons can cause hidden side effects if they’re in the store state unexpectedly.

Service Scope:

Provide a service in the root scope only if you’re sure it’s used across the entire app. Also singletons are great for optimization as they are included in tree-shaking (don’t forget to remove all direct links to singleton)
Otherwise, declare it in a specific module to limit reach. This approach also prevents unintentional singletons when you only need localized service instances

Avoid Dumping Grounds:

Keep services purposeful—don’t combine random utilities or unconnected logic into a single service
Organize code by functionality—auth, user profiles, analytics, etc.

State Management:

Use a service to store global state only after careful consideration
Adopt a formal state management library like NgRx for larger apps; it’s more predictable and test-friendly

State Management & Data Flow

Data flow patterns can make or break your Angular project. Even if your app is small now, inconsistent data handling could lead to major refactoring down the road.

Predictable Patterns:

Pick a state management approach—NgRx, Behavior Subject-based patterns, or a simpler store-service approach—and stick to it
Don’t switch patterns mid-project because it causes confusion

Immutable Updates:

Keep data immutable. Avoid mutating arrays or objects in place to prevent strange issues with Angular’s change detection
Make new objects instead of modifying existing ones

// Bad practice
export class ListComponent {
  @Input() list: Todo[] = [];

  // Bad: Directly mutating input array
  toggleListCompletion(item: ListItem): void {
    todo.completed = !todo.completed; // Change detection might miss this!
  }
}


// Good practice
export class ListComponent {
  @Input() list: ListItem[] = [];
  @Output() listChange = new EventEmitter();

  // Good: Creating new array with modified item
  onToggleListItem(listItem: ListItem): void {
    const updatedList = this.list.map(item => 
      item.id === listItem.id 
        ? { ...item, completed: !item.completed }
        : item
    );
    this.listChange.emit(updatedList);
  }
}

Subscriptions Housekeeping:

Use async pipes in templates whenever possible so that Angular handles subscription lifecycles for you
If you manually subscribe, remember to unsubscribe in ngOnDestroy()

Performance Optimization

No one likes a sluggish app. Angular’s built-in optimizations help, but you can do more to reduce load times and keep the UI responsive.

Lazy Loading:

Don’t load every feature upfront: this bogs down the initial experience
Lazy load your modules so users will only fetch what they need. Also, use a custom preload strategy to enhance the user experience even further

Check this piece of a large application which implemented a custom preload strategy to balance initial load time with navigation speed:

// app-routing.module.ts
import { NgModule } from '@angular/core';
import { RouterModule, Routes, PreloadAllModules } from '@angular/router';

const routes: Routes = [
  {
    path: 'dashboard',
    loadChildren: () => import('./dashboard/dashboard.module')
      .then(m => m.DashboardModule),
    data: { expectedRole: 'manager' }
  },
  {
    path: 'settings',
    loadChildren: () => import('./settings/settings.module')
      .then(m => m.SettingsModule),
    data: { expectedRole: 'superuser' }
  },
  // ...
];

// Custom preloading strategy which checks user role 
import { Injectable } from '@angular/core';
import { PreloadStrategy, Route } from '@angular/router';
import { Observable, of } from 'rxjs';
Import { RolesManagementService} from 'services/roles-management.service';

@Injectable({ providedIn: 'root' })
export class CustomPreloadStrategy implements PreloadStrategy{

  constructor(
    private rolesManager: RolesManagementService
  ) {}

  preload(route: Route, load: () => Observable): Observable {
    return this.rolesManager.hasRole(route.data.expectedRole).pipe(
        switchMap(hasRole => hasRole ? load() : of(null)),
      );
  }
}

OnPush Detection:

Use ChangeDetectionStrategy.OnPush for components that rely on immutable data and observables to reduce unnecessary checks, especially in large complex components (tables, forms) and real-time data updates
Profile your application to verify whether OnPush is truly cutting down on re-renders, and highlight any components that benefit most from it

Trim Dependencies:

Scan package.json regularly to identify large libraries that you don’t need. Even a single heavy library can balloon your bundle-size
Remove or replace dependencies that are rarely used (or can be replicated with native methods) to keep your build smaller and more efficient

Security Principles

Angular offers built-in defenses like DOM sanitization, but you still need to review your app for potential threats. Ignoring user input validation or logging sensitive info can lead to data breaches.

Prevent XSS Attacks:

Use Angular’s default sanitization for URLs, HTML, and styles. Don’t bypass these unless you know exactly why
Avoid direct innerHTML or bypassSecurityTrustHtml calls unless you’re absolutely sure the data is safe

Hidden Credentials:

Never keep API keys or private tokens in your source code
Double-check environment files, console logs, and debug statements for leaks

Dependency Scans:

Monitor and upgrade outdated third-party packages; they can expose your entire app
Tools like npm audit or SonarQube highlight vulnerabilities so you can patch them early
Integrate automated checks into your CI/CD pipeline, blocking merges if critical vulnerabilities appear

Comprehensive Testing

A robust test suite catches regressions before they reach production. Cover your components, services, and routing logic, focusing on critical paths first.

Unit Tests:

Use Angular’s TestBed for components, focusing on how they interact with services and user input
For services, test each method thoroughly, mocking network calls or external dependencies to isolate logic

Integration & E2E Tests:

Use frameworks like Cypress or Protractor (noting Protractor’s maintenance mode) to simulate real user flows, ensuring everything works together
Write tests for key user journeys—such as sign-up, checkout, and profile management—to uncover issues that may not surface in isolated unit tests

Meaningful Coverage:

A coverage percentage is just a number. You still need to check that your tests are actually verifying behavior, not just passing lines of code
Focus on quality over quantity. It’s better to have fewer, more meaningful tests that cover critical logic and edge cases than a high number of superficial tests that only inflate coverage stats

Your Angular Partner: Development & Audit Services

We’ve been harnessing Angular since its earliest days, delivering tailor-made solutions for tech-driven companies worldwide.

In the case of our client C!A, we used Angular to build a robust front-end for their web-app Current. Current is a public service delivery system used by government officials in 10+ US state and county agencies to handle thousands of service requests nationwide. If you’d like to learn more, take a look at the case study.

Our work with CDP Blitz involved refactoring complex logic into lean components and services, boosting stability, cutting page load times, and exposing hidden bottlenecks early on.

Meanwhile, with PageFreezer—a digital archiving and compliance solution—we helped integrate advanced user permission management, refine data archiving workflows, and introduce systematic testing to keep code quality high under heavy data loads. Feel free to check out the full case study for more details.

In every engagement, we aim to fine-tune Angular apps to remain stable, secure, and ready for new features. If you’re curious about how we tackle front-end tasks in Angular, React, or Vue, check out our web development page or drop by our blog for more insights. And if you’re thinking of upgrading your Angular codebase or building something from scratch, we’re here to turn your ideas into real-world solutions.

By following this Angular code review checklist, you’ll build maintainable, high-performing apps that stand the test of time. Keep refining your processes as your frameworks evolve, and reach out if you’re ready to push your project’s boundaries even further. We love working with folks who, like us, enjoy turning good ideas into great software.

Takeaways

This concludes our condensed Angular Code Review Checklist. By following these points, you’ll dodge many hidden (and obvious) pitfalls throughout your journey. Remember to keep an eye on code style, watch your dependencies, and never forget about security. If you spot trouble or feel stuck, let’s connect. We love helping fellow developers refine and enhance their apps.

We’ve been doing this since 2005, and we’re eager to see your Angular project grow. When your code is clear, your users feel it. Let’s make that happen.