@launchdarkly/js-server-sdk-common

What is @launchdarkly/js-server-sdk-common?

@launchdarkly/js-server-sdk-common is a common library for LaunchDarkly's JavaScript server-side SDKs. It provides core functionality for feature flag evaluation, user targeting, and other feature management capabilities.

What are @launchdarkly/js-server-sdk-common's main functionalities?

Feature Flag Evaluation

This feature allows you to evaluate feature flags for a given user. The code sample demonstrates how to initialize the client, wait for it to be ready, and then evaluate a feature flag for a specific user.

const { LDClient } = require('@launchdarkly/js-server-sdk-common');
const client = new LDClient('YOUR_SDK_KEY');

client.on('ready', () => {
  const user = { key: 'user123' };
  const showFeature = client.variation('your-feature-flag-key', user, false);
  console.log(`Feature flag value: ${showFeature}`);
});

User Targeting

This feature allows you to target specific users based on their attributes. The code sample shows how to include user attributes like email in the evaluation process.

const { LDClient } = require('@launchdarkly/js-server-sdk-common');
const client = new LDClient('YOUR_SDK_KEY');

client.on('ready', () => {
  const user = { key: 'user123', email: '[e-mail]' };
  const showFeature = client.variation('your-feature-flag-key', user, false);
  console.log(`Feature flag value for user: ${showFeature}`);
});

Event Tracking

This feature allows you to track custom events for analytics and reporting. The code sample demonstrates how to track a custom event for a specific user.

const { LDClient } = require('@launchdarkly/js-server-sdk-common');
const client = new LDClient('YOUR_SDK_KEY');

client.on('ready', () => {
  const user = { key: 'user123' };
  client.track('custom-event', user, { key: 'value' });
  console.log('Custom event tracked');
});

Other packages similar to @launchdarkly/js-server-sdk-common

flagr

Flagr is an open-source feature flagging and A/B testing tool. The flagr package provides feature flag evaluation and user targeting functionalities. It is comparable to @launchdarkly/js-server-sdk-common but is open-source and can be customized to fit specific needs.

README

LaunchDarkly SDK JavaScript Common Server Code

This project contains Typescript classes and interfaces that are applicable to server-side SDKs.

This library is a beta version and should not be considered ready for production use while this message is visible.

Contributing

See Contributing.

About LaunchDarkly

• LaunchDarkly is a continuous delivery platform that provides feature flags as a service and allows developers to iterate quickly and safely. We allow you to easily flag your features and manage them from the LaunchDarkly dashboard. With LaunchDarkly, you can:
  • Roll out a new feature to a subset of your users (like a group of users who opt-in to a beta tester group), gathering feedback and bug reports from real-world use cases.
  • Gradually roll out a feature to an increasing percentage of users, and track the effect that the feature has on key metrics (for instance, how likely is a user to complete a purchase if they have feature A versus feature B?).
  • Turn off a feature that you realize is causing performance problems in production, without needing to re-deploy, or even restart the application with a changed configuration file.
  • Grant access to certain features based on user attributes, like payment plan (eg: users on the ‘gold’ plan get access to more features than users in the ‘silver’ plan). Disable parts of your application to facilitate maintenance, without taking everything offline.
• LaunchDarkly provides feature flag SDKs for a wide variety of languages and technologies. Check out our documentation for a complete list.
• Explore LaunchDarkly
  • launchdarkly.com for more information
  • docs.launchdarkly.com for our documentation and SDK reference guides
  • apidocs.launchdarkly.com for our API documentation
  • blog.launchdarkly.com for the latest product updates