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Be Constructive

Let’s look at how to give constructive feedback in code reviews. We’ll show you a simple example and explain why the feedback matters.

The Scenario

A developer has written a function to calculate the total price of items in a shopping cart. The code may work but could be improved.

calculateTotal.ts
// Before
function calculateTotal(items) {
  let total = 0
  for (let i = 0; i < items.length; i++) {
    total += items.price
  }
  return total
}

PR Comment

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

// After
function calculateTotal(items) {
  return items.reduce((total, item) => total + item.price, 0)
}

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Improvements

1. Code Clarity

  • The reduce method clearly shows we’re combining all items into a single value
  • The code is more declarative, showing what we want to do rather than how to do it
  • Less code means fewer places for bugs to hide

2. Edge Case Handling

  • reduce with an initial value of 0 handles empty arrays correctly
  • The original code would also work with empty arrays, but it’s not as obvious
  • The new version makes the behavior more explicit

3. Bug Prevention

  • The original code had a potential bug: items.price instead of items[i].price
  • The new version makes it impossible to make this mistake
  • The structure of reduce forces us to handle each item correctly

Tips

1. Start Positive

  • Acknowledge what works well
  • Show you understand the code’s purpose
  • Example: “Great work on the total calculation!“

2. Explain Your Suggestions

  • Why is your suggestion better?
  • What problems does it solve?
  • Example: “The reduce method makes the code more concise and easier to read.”

3. Be Specific

  • Point to exact lines or patterns
  • Provide clear examples
  • Example: “This handles edge cases better, like an empty array.”

4. Keep It Friendly

  • Use encouraging language
  • Focus on improvement, not criticism
  • Example: “Thanks for making it more readable!”

Common Pitfalls to Avoid

1. Being Too Critical

  • ❌ “This code is wrong. You should use reduce.”
  • ✅ “Great work! Here’s a suggestion to make it even better.”

2. Not Explaining Why

  • ❌ “Use reduce instead.”
  • ✅ “Using reduce makes the code more concise and handles edge cases better.”

3. Ignoring the Positive

  • ❌ “This needs improvement.”
  • ✅ “Good work! Here’s how we can make it even better.”

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

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