LaunchDarkly SDK for Node.js

Quick setup

0. Install the Node.js SDK with npm

    npm install ldclient-node --save
   

1. Require the LaunchDarkly client:

    var LaunchDarkly = require('ldclient-node');
   

2. Create a new LDClient with your SDK key:

    var ld_client = LaunchDarkly.init("YOUR SDK KEY")
   

Your first feature flag

1. Create a new feature flag on your dashboard

2. In your application code, use the feature's key to check whether the flag is on for each user:

    ld_client.once('ready', function() {
      ld_client.toggle("your.flag.key", {"key" : "[email protected]"}, false, function(err, show_feature) {
        if (show_feature) {
            # application code to show the feature
        }
        else {
            # the code to run if the feature is off 
        }
      });
    });
   

Learn more

Check out our documentation for in-depth instructions on configuring and using LaunchDarkly. You can also head straight to the complete reference guide for this SDK.

Contributing

We encourage pull-requests and other contributions from the community. We've also published an SDK contributor's guide that provides a detailed explanation of how our SDKs work.

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
  • Java
  • [JavaScript] (http://docs.launchdarkly.com/docs/js-sdk-reference "LaunchDarkly JavaScript SDK")
  • [PHP] (http://docs.launchdarkly.com/docs/php-sdk-reference "LaunchDarkly PHP SDK")
  • [Python] (http://docs.launchdarkly.com/docs/python-sdk-reference "LaunchDarkly Python SDK")
  • [Go] (http://docs.launchdarkly.com/docs/go-sdk-reference "LaunchDarkly Go SDK")
  • [Node.JS] (http://docs.launchdarkly.com/docs/node-sdk-reference "LaunchDarkly Node SDK")
  • [.NET] (http://docs.launchdarkly.com/docs/dotnet-sdk-reference "LaunchDarkly .Net SDK")
  • [Ruby] (http://docs.launchdarkly.com/docs/ruby-sdk-reference "LaunchDarkly Ruby SDK")
  • [Python Twisted] (http://docs.launchdarkly.com/docs/python-twisted "LaunchDarkly Python Twisted SDK")
• Explore LaunchDarkly
  • [www.launchdarkly.com] (http://www.launchdarkly.com/ "LaunchDarkly Main Website") for more information
  • [docs.launchdarkly.com] (http://docs.launchdarkly.com/ "LaunchDarkly Documentation") for our documentation and SDKs
  • [apidocs.launchdarkly.com] (http://apidocs.launchdarkly.com/ "LaunchDarkly API Documentation") for our API documentation
  • [blog.launchdarkly.com] (http://blog.launchdarkly.com/ "LaunchDarkly Blog Documentation") for the latest product updates