Node.js SDK

FeatureProbe is an open source feature management service. This SDK is used to control features in Node.js programs. This SDK is designed primarily for use in multi-user systems such as web servers and applications.

SDK quick links

Resource	Location
SDK API documentation	SDK API docs
GitHub repository	Server-SDK for Node.js
Sample applications	Demo code (JavaScript)
Published module	npm

tip

For users who are using FeatureProbe for the first time, we strongly recommend that you return to this article to continue reading after reading the Gradual Rollout Tutorial.

Notice

For users who needs to use metric analysis, please upgrade JavaScript SDK to version 2.0.1 .

Step-by-Step Guide

Backend projects usually only need to instantiate a FeatureProbe SDK (Client).

According to the requests of different users, call the FeatureProbe Client to obtain the toggle result for each user.

info

The server-side SDK uses an asynchronous connection to the FeatureProbe server to pull judgment rules, and the judgment rules will be cached locally. All interfaces exposed to user code only involve memory operations, so there is no need to worry about performance issues when calling.

Step 1. Install the Node.js SDK

First, install the FeatureProbe SDK as a dependency in your application.

NPM

npm install featureprobe-server-sdk-node --save

Step 2. Create a FeatureProbe instance

After you install the SDK, import it, then create a single, shared instance of the FeatureProbe SDK.

const fp = new FeatureProbe({
    remoteUrl: 'https://featureprobe.io/server',  // or https://127.0.0.1:4007
    serverSdkKey: /* FEATURE_PROBE_SERVER_SDK_KEY mentioned above */,
    refreshInterval: 5000,
});

await fp.start(1000);  // wait for up to 1 second for the first refresh
// await fp.start();  // init with time limit

Step 3. Use the feature toggle

You can use sdk to check which variation a particular user will receive for a given feature flag.

const user = new User(/* uniqueUserId for percentage rollout */);
user.with('ATTRIBUTE_NAME_IN_RULE', VALUE_OF_ATTRIBUTE);  // call with() for each attribute, or extendAttrs(attributeMap) for attributes

const boolValue = fp.booleanValue('YOUR_TOGGLE_KEY', user, false);
if (boolValue) {
   // the code to run if the toggle is on
} else {
   // the code to run if the toggle is off
}

Step 4. Close FeatureProbe Client before program exits

Close the client before exiting to ensure accurate data reporting.

await fp.close();

Track Events

note

The Node.js SDK supports event tracking from version 2.0.1.

The event tracking feature can record the actions taken by the user in the application as events.

Events are related to toggle's metrics. For more information about event analysis, please read Event Analysis.

fp.track("YOUR_CUSTOM_EVENT_NAME", user);
// Providing a metric value to track
fp.track("YOUR_CUSTOM_EVENT_NAME", user, 5.5);

Customize SDK

tip

This paragraph applies to users who want to customize this SDK, or contribute code to this SDK through the open source community. Other users can skip this section.

We provide an acceptance test of this SDK to ensure that the modified SDK is compatible with the native rules of FeatureProbe. Integration test cases are added as submodules of each SDK repository. So be sure to pull the submodule first to get the latest integration tests before running the tests.

git submodule update --init --recursive
git pull --recurse-submodules
npm run test