launchdarkly-js-client-sdk

What is launchdarkly-js-client-sdk?

The launchdarkly-js-client-sdk is a JavaScript SDK for LaunchDarkly, a feature management platform that allows developers to control the release of features to users. This SDK enables you to manage feature flags, perform A/B testing, and roll out new features gradually.

What are launchdarkly-js-client-sdk's main functionalities?

Initialize the client

This code initializes the LaunchDarkly client with your environment key and a user object. The client is ready to be used once the 'ready' event is fired.

const LDClient = require('launchdarkly-js-client-sdk');
const client = LDClient.initialize('YOUR_ENVIRONMENT_KEY', { key: 'user_key' });
client.on('ready', () => {
  console.log('LaunchDarkly client is ready');
});

Evaluate feature flags

This code evaluates a feature flag and returns its value. If the feature flag is enabled, it will log 'Feature is enabled'; otherwise, it will log 'Feature is disabled'.

client.on('ready', () => {
  const showFeature = client.variation('your-feature-flag-key', false);
  if (showFeature) {
    console.log('Feature is enabled');
  } else {
    console.log('Feature is disabled');
  }
});

Track custom events

This code tracks a custom event with a specified key and optional data. This can be useful for analytics and monitoring user interactions.

client.track('custom-event-key', { customData: 'value' });

Identify users

This code identifies a new user with a unique key and optional attributes. This is useful for targeting specific users with feature flags.

client.identify({ key: 'new_user_key', name: 'New User' }).then(() => {
  console.log('User identified');
});

Other packages similar to launchdarkly-js-client-sdk

unleash-client

Unleash is an open-source feature management solution. The unleash-client package provides similar functionality to LaunchDarkly, allowing you to manage feature flags and control feature rollouts. However, Unleash is self-hosted, which means you need to manage the infrastructure yourself.

configcat-js

ConfigCat is a feature flag and configuration management service. The configcat-js package allows you to manage feature flags and configurations in your JavaScript applications. ConfigCat offers a hosted solution with a user-friendly interface, similar to LaunchDarkly.

flagsmith

Flagsmith is an open-source feature flag and remote config service. The flagsmith package provides similar functionality to LaunchDarkly, including feature flag management and user targeting. Flagsmith can be used as a hosted service or self-hosted, offering flexibility in deployment.

README

LaunchDarkly SDK for JavaScript - Main Package

This file contains the launchdarkly-js-client-sdk package, which is the standard interface for the LaunchDarkly SDK for browser JavaScript. It is described in the main README.

This package automatically imports launchdarkly-js-sdk-common, which provides much of the underlying implementation.

Changelog

[2.12.1] - 2019-06-28

Added:

• The SDK now logs a message at info level when the stream connection is started or stopped. It also logs a message at warn level if it detects that the stream had to be restarted due to a connection failure; however, in browsers that have native support for EventSource, connection restarts may be handled internally by the browser in which case there will be no log message.

Fixed:

• Under some circumstances, the SDK would fail to restart a streaming connection if it had already been dropped and restarted before. This normally would not happen when using a built-in browser implementation of EventSource, but could happen with some EventSource polyfills.
• Fixed a broken link in the project README.