Best Practices
6 min read
Updated January 2025
Code Review Best Practices
Proven strategies for conducting effective code reviews that improve code quality, share knowledge, and build stronger development teams.
Best Practices for PR Authors
Keep Changes Small and Focused
❌ Too Large
Files changed: 23
Lines added: +847
Lines deleted: -234
• User authentication system
• Database schema changes
• Frontend UI updates
• Email notifications
• Bug fixes in payment flow
• Database schema changes
• Frontend UI updates
• Email notifications
• Bug fixes in payment flow
✅ Right Size
Files changed: 4
Lines added: +127
Lines deleted: -15
• Add JWT middleware
• Update auth routes
• Add auth tests
• Update documentation
• Update auth routes
• Add auth tests
• Update documentation
Why Size Matters
Review Quality
Large PRs get shallow reviews. Reviewers miss issues.
Review Speed
Small PRs reviewed in hours, not days.
Risk Reduction
Easier to revert, less chance of breaking changes.
Always Self-Review Before Submitting
Self-Review Checklist
Real Example: What Self-Review Catches
# Found during self-review:
- console.log("debugging user data:", userData);
- // TODO: optimize this later
- const tempVar = processData(); // unused
+ // Clean, production-ready code
Self-review prevents 60% of reviewer comments on basic issues.
Write Clear PR Descriptions
❌ Vague Description
Title: Fix bug
Description: Fixed the issue
✅ Clear Description
Title: Fix user authentication timeout bug
Description:
**What:** Fix JWT token expiration handling
**Why:** Users logged out after 1 hour unexpectedly
**How:** Extended default timeout to 24 hours
**Testing:** Verified with staging environment
PR Description Template
## Changes
- Brief bullet point summary
- What files were modified and why
## Context
- Link to ticket/issue: #123
- Business context or user story
## Testing
- Unit tests added/updated
- Manual testing performed
## Risks
- Breaking changes (if any)
- Database migrations
- Performance implications
Best Practices for Reviewers
Review Systematically
Review Order (Most Effective)
1
Read PR description and linked issues
Understand the WHY
2
Look at test files first
Understand expected behavior
3
Review main logic files
Check implementation against tests
4
Check configuration/infrastructure changes
Deployment and environment impact
5
Review documentation updates
User-facing changes explained
What to Look For
🔍 Logic & Correctness
- • Does the code do what the PR says?
- • Are edge cases handled?
- • Is error handling appropriate?
- • Are there potential race conditions?
⚡ Performance & Security
- • Any N+1 query problems?
- • Input validation present?
- • Sensitive data properly handled?
- • Memory leaks possible?
Give Constructive, Specific Feedback
❌ Poor Feedback
"This is wrong"
"Bad performance"
"Doesn't follow patterns"
"I don't like this approach"
Vague, unhelpful, no suggested improvement
✅ Good Feedback
"Missing null check on line 42. Add: if (!user) return null;"
"N+1 query issue. Consider using .includes() or batch loading."
"Use our UserService pattern for consistency with auth module."
"Strategy pattern might be cleaner here. Example: ..."
Specific, actionable, includes solutions
Feedback Categories
🚨 Critical (Must Fix)
Security issues, logic errors, breaking changes
Example: "SQL injection vulnerability - use parameterized queries"
⚠️ Important (Should Fix)
Performance issues, maintainability concerns
Example: "This could cause memory leaks with large datasets"
💡 Suggestion (Nice to Have)
Code style, optimizations, alternatives
Example: "Consider using Array.map() for better readability"
Review Promptly
✅ Good Response Times
Hot fixes: < 2 hours
Small PRs: Same day
Large PRs: 1-2 days
Non-urgent: < 3 days
⚠️ Team Impact
Delayed reviews block deployments
Context switching costs increase
Team velocity decreases
💡 If You're Busy
Leave a quick "reviewing soon" comment
Suggest another reviewer
Give partial feedback and continue later
Team-Level Best Practices
Establish Review Standards
Team Agreement Template
# Code Review Standards
## PR Size Limits
- Max 400 lines changed per PR
- Break large features into smaller chunks
## Required Reviews
- 1 approval for minor changes
- 2 approvals for critical systems
- Security team review for auth changes
## Response Time Goals
- Initial review: 24 hours
- Follow-up reviews: 8 hours
- Hotfixes: 2 hours
Avoid Common Team Pitfalls
❌ Pitfalls
- • Review fatigue from oversized PRs
- • Bikeshedding on style preferences
- • Senior developers become bottlenecks
- • Inconsistent standards across team
- • Personal attacks or harsh criticism
✅ Solutions
- • Enforce PR size limits with automation
- • Use code formatters to eliminate style debates
- • Rotate reviewers, encourage junior participation
- • Document and automate standards checking
- • Focus feedback on code, not person
