Chart.js Data Visualization: Beautiful Charts for Web

The Feature That Broke Production (Feature Flags Could Have Saved Us)

We deployed a bug to all users at once. Feature flags would have contained the damage.

Table of Contents

• Modern Development 2026
• Core Concepts
• 5 Essential Patterns
• Implementation
• Best Practices
• Testing Strategy
• Rollout Plans
• FAQ
• Production Guide

Modern Development 2026

Ship fast, fail safely.

Progressive Delivery

Release features gradually.

A/B Testing

Test variations with real users.

Core Concepts

Understanding the fundamentals.

Feature Flags

// Control features remotely
if (featureFlags.isEnabled('new-checkout')) {
  return <NewCheckout />;
} else {
  return <OldCheckout />;
}

Pattern 1: Simple Toggle

Boolean Flags

const flags = {
  newUI: true,
  betaFeatures: false
};

Pattern 2: Percentage Rollout

Gradual Release

Show to 10% of users, then 50%, then 100%.

Pattern 3: User Targeting

Segments

Different features for different users.

Pattern 4: A/B Testing

Experiments

Test which variant performs better.

Pattern 5: Kill Switch

Emergency Disable

Turn off broken features instantly.

Implementation

Quick setup guide.

Best Practices

Use flags wisely.

Testing

Test all flag combinations.

Performance

FAQ

Q1: When to use?

For risky features and experiments.

Q2: Technical debt?

Clean up old flags regularly.

Q3: Cost?

Free tier sufficient for most.

Q4: Performance impact?

Negligible with caching.

Q5: Testing complexity?

Test both flag states.

Conclusion

Feature flags enable safe deployments.

Ship confidently.