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LearnCode ReviewCode StructureDomain Types

Domain Types

Let’s look at how to suggest improvements for domain types in code reviews. We’ll show you a simple example and explain why the feedback matters.

The Scenario

A developer has written code to handle user data. The code works but could benefit from more specific types.

createUser.ts
// Before
function createUser(data: any) {
  return {
    name: data.name,
    age: data.age,
    email: data.email,
  }
}

PR Comment

Choose the comment that you think is the most constructive and helpful.

// After
interface User {
  name: string
  age: number
  email: string
}
 
function createUser(data: User) {
  return {
    name: data.name,
    age: data.age,
    email: data.email,
  }
}

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Improvements

1. Type Safety

  • Catches errors at compile time
  • Prevents runtime type issues
  • Better IDE support

2. Code Quality

  • More maintainable code
  • Better documentation
  • Clearer expectations

3. Developer Experience

  • Better autocomplete
  • Easier refactoring
  • Clearer interfaces

Tips

1. Start Positive

  • Acknowledge the working code
  • Show you understand the current approach
  • Example: “Great work on the user creation!“

2. Explain the Benefits

  • Why do types matter?
  • How do they help?
  • Example: “This improves type safety”

3. Be Specific

  • Suggest concrete improvements
  • Explain why they matter
  • Example: “Adding a proper User interface helps catch errors early”

4. Keep It Friendly

  • Focus on improvement, not criticism
  • Use encouraging language
  • Example: “Thanks for considering type safety!”

Common Pitfalls to Avoid

1. Being Too Critical

  • ❌ “This needs proper types.”
  • ✅ “Good work! Here’s how we can make it even more type-safe.”

2. Not Explaining Why

  • ❌ “Add an interface.”
  • ✅ “Adding an interface helps catch errors early.”

3. Ignoring the Positive

  • ❌ “This needs type definitions.”
  • ✅ “Great work! Here’s how we can make it even more maintainable.”

Remember: The goal is to help your teammate write better code while maintaining a positive and collaborative environment!

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