LaunchDarkly JavaScript SDK Eases Feature Flag Management

Introduction

Feature flags empower developers to toggle features in applications without new code deployments. The open source LaunchDarkly JavaScript SDK simplifies robust feature flagging in JavaScript web apps. It works for both vanilla JS and popular frameworks like React, Angular, and Vue.js.

With the LaunchDarkly JS SDK, teams can instantly turn features on/off, target users, gradually roll out changes, run A/B tests, and more—with no redeployment needed. This allows decoupling feature releases from code deployment for faster, lower-risk delivery. Keep reading to learn the key capabilities, setup instructions, and best practices when using the LaunchDarkly JavaScript SDK for feature management.

Key Capabilities

The LaunchDarkly JS SDK enables diverse feature flag use cases with precise control and progressive delivery options.

Instant Feature Activation

Activate or deactivate features immediately without redeploying code. Dashboard changes to targeting rules take effect right away. Features are managed separately from code for continuous delivery.

Granular User Targeting

Target and roll out features to specific user segments based on attributes like email, user ID, account tier, and more. Custom rules provide unlimited targeting combinations. Manage access with precision.

Gradual Rollouts

Roll out features to a percentage of users first, then ramp up to more users over time. Reduces risk and allows incremental testing before full launch. SDK provides rollout analytics.

A/B Testing

Easily A/B test feature flag variations using the visual editor. Target groups for each variant, then compare metrics to find the best performer.

CI/CD Integration

Connect to pipelines and workflows. Create dev, test, prod environments with environment-specific flags. Enforce consistent, surprise-free releases.

Getting Started Guide

Follow these steps to start using the LaunchDarkly JS SDK:

Sign Up for LaunchDarkly

First, go to LaunchDarkly and create an account. Select a plan suitable for your needs. Collaborate with team members and customize roles.

Install the JS SDK

Use npm to install in Node.js apps:

npm install launchdarkly-js-client-sdk

For front-end frameworks, use:

yarn add launchdarkly-js-client-sdk

Or link directly via CDN.

Initialize the SDK

When initializing your app, pass your LaunchDarkly API key:

const ldClient = LaunchDarkly.init("API_KEY");

Set the client-side user ID and custom attributes:

ldClient.identify({
  key: 'user123',
  email: 'user@company.com',
  plan: 'premium' 
});

Create Feature Flags

In LaunchDarkly, make flags for your features. Define targeting, variations, environments, and more.

Check Flags in Code

In your app code, check flag values to conditionally show features:

if (ldClient.variation('betaFeature', false)) {
  // Flag is on, show feature
} else {
  // Flag off, hide feature
} 

Best Practices

Follow these tips to effectively use the LaunchDarkly JS SDK:

• Abstract flag logic into a separate module to avoid scattered checks.

• Build reusable helpers like isFeatureEnabled() to reduce duplicate code.

• Organize flags logically with a naming convention like feature-checkout.

• Fully document each flag's purpose and behavior in LaunchDarkly.

• Regularly review and remove old, unused flags to prevent clutter.

• Plan rollbacks in case issues arise with a flag.

• Test flags locally before pushing to production.

Conclusion

The LaunchDarkly JavaScript SDK gives teams instant control and progressive delivery options for features. With user targeting, canary launches, A/B tests, and CI/CD integration, developers can release faster with less risk. For any JavaScript web app, LaunchDarkly's SDK is an essential tool for adopting continuous delivery and experimentation.

Check out the LaunchDarkly docs for more tips, examples, and advanced configuration options. Ready to get started managing features like a pro? Explore LaunchDarkly today to take your application development to the next level.