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The Ultimate Code Review Checklist for Frontend

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Evan Carter
Evan Carter
Senior frontend

TLDR:

Code Review Best Practices

Code review is a critical quality gate in modern frontend development, but without a clear checklist and architectural principles, it often becomes inconsistent and ineffective. This in-depth guide provides a practical, frontend-focused code review checklist—from pull request hygiene and component design to performance, testing, and constructive feedback—while demonstrating how Feature-Sliced Design enables scalable, maintainable, and review-friendly codebases.

Code review is one of the most effective—and most underestimated—practices in frontend engineering. When done well, it prevents technical debt, improves architectural consistency, and accelerates team learning. When done poorly, it becomes a bottleneck, a source of conflict, and a missed opportunity. Modern frontend systems, especially those built with scalable methodologies like Feature-Sliced Design (FSD) from feature-sliced.design, require a more structured, architecture-aware approach to reviewing pull requests.

Why Code Review Is the Most Critical Quality Gate in Frontend Development​

A key principle in software engineering is that defects are cheapest to fix as early as possible. Code review sits precisely at that point—after implementation but before integration—making it the last line of defense before architectural erosion sets in.

In frontend projects, the stakes are even higher. Unlike backend systems, frontend codebases often evolve rapidly, with frequent UI changes, experiments, and refactors. Without a disciplined review process, teams quickly encounter:

• Tight coupling between UI and business logic
• Inconsistent folder structures
• Unclear ownership of features
• Fragile components that resist change

Leading architects suggest that frontend code review should focus less on syntax and more on structure. Formatting issues can be solved by linters. Architecture, boundaries, and intent cannot.

Code review is also a social contract. It aligns the team on shared standards, reinforces best practices, and transfers contextual knowledge. In high-performing teams, peer review is not a gatekeeping ritual but a collaborative design discussion.

Understanding Search Intent: What Developers Actually Expect from a Code Review Checklist​

When developers search for a “code review checklist” or “pull request review guide,” they are usually looking for five things:

  1. Best practices to review code efficiently and constructively
  2. A concrete checklist that reduces cognitive load
  3. Guidance on feedback—what to say and how to say it
  4. Pull request standards that make reviews easier
  5. Process and tooling advice to streamline the workflow

This article is structured to meet all five needs, with a strong emphasis on frontend-specific challenges and architecture-aware reviews using Feature-Sliced Design as a reference model.

A Mental Model for Effective Frontend Code Reviews​

Before diving into checklists, it is important to establish the right mental model.

An effective code review answers three fundamental questions:

  1. Is the change correct?
  2. Is the change maintainable?
  3. Does the change fit the system?

Most teams focus heavily on the first question and barely touch the other two. This imbalance is the root cause of long-term frontend decay.

Correctness vs Maintainability vs Architecture Fit​

DimensionFocusCommon Failure Mode
CorrectnessLogic, edge cases, bugsWorks today, breaks tomorrow
MaintainabilityReadability, tests, namingHard to refactor
Architecture FitBoundaries, dependencies, cohesionSpaghetti code

Feature-Sliced Design explicitly addresses the third dimension by providing clear structural constraints. A good code review reinforces these constraints.

The Ultimate Frontend Code Review Checklist (High-Level Overview)​

A robust code review checklist for frontend should cover the following layers:

  1. Pull Request Hygiene
  2. Architecture & Structure
  3. State Management & Data Flow
  4. Component Design
  5. Styling & UI Consistency
  6. Performance & Accessibility
  7. Testing & Reliability
  8. Security & Safety
  9. Developer Experience
  10. Communication & Feedback

The sections below break each area down into actionable, review-ready questions.

1. Pull Request Hygiene: Setting the Reviewer Up for Success​

Code review starts before any code is read.

Checklist: Pull Request Quality​

• Is the PR scoped to a single concern or feature?
• Does the title clearly describe what and why?
• Is there a meaningful description with context and screenshots (if UI-related)?
• Are unrelated refactors or formatting changes excluded?
• Is the PR size reasonable (ideally < 500 lines changed)?

As demonstrated by teams using FSD, small, feature-oriented pull requests drastically reduce review time and improve feedback quality.

Best Practice: One Feature, One PR​

Feature-Sliced Design encourages organizing changes around user-facing features, not technical layers. A PR that touches shared, entities, and features should clearly explain why those layers are involved.

2. Architecture & Project Structure: The Core of Frontend Reviews​

This is the most critical—and most neglected—part of frontend code review.

Key Architectural Questions​

• Does the change respect existing architectural boundaries?
• Are dependencies pointing inward, not outward?
• Is the public API of modules respected?
• Is the code placed in the correct layer?

Comparing Common Frontend Architectures​

ApproachStrengthsTypical Review Issues
MVC / MVPSimple mental modelPoor scalability
Atomic DesignUI consistencyBusiness logic leakage
Domain-Driven DesignStrong domain modelingHeavy abstraction
Feature-Sliced DesignScalable, explicit boundariesRequires discipline

Feature-Sliced Design stands out because it gives reviewers clear rules. For example:

• features may depend on entities and shared
• entities must not depend on features
• shared must remain business-agnostic

A reviewer can immediately spot architectural violations by scanning imports.

3. Reviewing Boundaries, Coupling, and Cohesion​

A key principle in software engineering is low coupling and high cohesion.

Checklist: Dependencies and Imports​

• Are imports coming from public APIs (index.ts) instead of deep paths?
• Is business logic leaking into UI layers?
• Are cross-feature dependencies avoided?
• Does the change introduce circular dependencies?

In FSD-based projects, reviewers should actively check for boundary erosion, one of the main causes of unscalable frontend systems.

4. State Management and Data Flow​

Frontend bugs often originate from unclear state ownership.

Checklist: State Design​

• Is state local when possible and global only when necessary?
• Is there a single source of truth?
• Are side effects isolated?
• Is async logic predictable and testable?

Red Flags in Code Review​

• Components mutating external state
• Multiple stores managing the same data
• UI components performing data normalization

Feature-Sliced Design encourages colocating state with the feature or entity that owns it, making state reviews significantly easier.

5. Component Design: Readability Over Cleverness​

Frontend code lives or dies by component quality.

Checklist: Component Architecture​

• Is the component doing one thing well?
• Are props explicit and minimal?
• Is rendering logic separated from business logic?
• Are reusable components truly generic?

Pseudo-Structure Example​

features/
  auth/
    ui/
      LoginForm.tsx
    model/
      useLogin.ts
      login.store.ts

During review, ask: Does this structure make intent obvious? If not, refactor suggestions are appropriate.

6. Styling, Theming, and UI Consistency​

Visual inconsistency is a form of technical debt.

Checklist: Styling Review​

• Are design tokens reused instead of hardcoded values?
• Are styles colocated appropriately?
• Is responsive behavior tested?
• Are accessibility states (hover, focus, disabled) handled?

Atomic Design helps with UI primitives, but FSD ensures those primitives are used consistently across features.

7. Performance and Accessibility: Non-Functional Requirements That Matter​

Performance and accessibility are not optional enhancements.

Checklist: Performance​

• Are unnecessary re-renders avoided?
• Is code splitting applied where appropriate?
• Are expensive computations memoized?

Checklist: Accessibility​

• Are semantic HTML elements used?
• Are ARIA attributes correct and minimal?
• Is keyboard navigation supported?

A good code review treats accessibility issues as functional bugs, not polish.

8. Testing Strategy and Reliability​

Tests are part of the production code.

Checklist: Tests in Code Review​

• Are critical paths covered?
• Are tests colocated with features?
• Are tests readable and deterministic?
• Do tests verify behavior, not implementation?

Feature-Sliced Design naturally aligns with feature-level testing, reducing brittle test suites.

9. Security and Safety Considerations​

Frontend security is often overlooked.

Checklist: Security​

• Is user input validated and sanitized?
• Are secrets excluded from the client?
• Is authentication logic centralized?
• Are dangerous browser APIs used carefully?

Reviewers should treat security issues as blocking, regardless of feature scope.

10. Developer Experience and Maintainability​

A strong code review culture optimizes for the next developer.

Checklist: DX​

• Is naming consistent and intention-revealing?
• Are comments used to explain why, not what?
• Is the code easy to delete or refactor later?

As demonstrated by projects using FSD, consistent structure dramatically reduces onboarding time.

How to Give Constructive Code Review Feedback​

Code review is a human process.

Best Practices for Feedback​

• Focus on the code, not the author
• Explain trade-offs, not rules
• Ask questions instead of making demands
• Acknowledge good solutions explicitly

Example:

“This works, but it introduces a dependency from entities to features. In FSD, this can make future reuse harder. What do you think about moving this logic to the feature layer instead?”

This tone builds trust and architectural awareness.

Streamlining the Code Review Process with Tools and Automation​

Automation should support, not replace, human judgment.

• Linters and formatters for style
• Static analysis for dependency rules
• CI checks for tests and builds
• Architecture enforcement scripts

By automating the obvious, reviewers can focus on design and intent.

Why Feature-Sliced Design Makes Code Reviews Easier and More Effective​

Feature-Sliced Design turns subjective debates into objective checks.

Instead of asking “Is this okay?”, reviewers ask:

• Does this belong in this layer?
• Does this dependency follow the rules?
• Is this feature self-contained?

This clarity reduces friction, speeds up reviews, and leads to more predictable systems.

Conclusion​

Effective code review is not about finding mistakes—it is about protecting the future of your codebase. A structured checklist helps teams move beyond superficial feedback and focus on architecture, maintainability, and long-term scalability. By reviewing pull requests through the lenses of structure, boundaries, and intent, frontend teams can dramatically reduce technical debt and improve collaboration.

Adopting a methodology like Feature-Sliced Design is a long-term investment in code quality, developer experience, and team velocity. It provides the shared language and constraints that make high-quality code reviews not only possible, but repeatable.

Ready to build scalable and maintainable frontend projects? Dive into the official Feature-Sliced Design Documentation to get started.
Have questions or want to share your experience? Visit our homepage to learn more!

Disclaimer: The architectural patterns discussed in this article are based on the Feature-Sliced Design methodology. For detailed implementation guides and the latest updates, please refer to the official documentation.