Node.js

Install dependencies

The first things we will do is install the Open Feature SDK and the GO Feature Flag provider.

yarn

yarn add @openfeature/server-sdk @openfeature/go-feature-flag-provider

npm

npm i @openfeature/server-sdk @openfeature/go-feature-flag-provider

Initialize your Open Feature client

To evaluate the flags you need to have an Open Feature configured in your app. This code block shows you how you can create a client that you can use in your application.

JavaScript

const {OpenFeature} = require("@openfeature/server-sdk");
const {GoFeatureFlagProvider} = require("@openfeature/go-feature-flag-provider");


// init Open Feature SDK with GO Feature Flag provider
const goFeatureFlagProvider = new GoFeatureFlagProvider({
  endpoint: 'http://localhost:1031/' // DNS of your instance of relay proxy
});
OpenFeature.setProvider(goFeatureFlagProvider);
const featureFlagClient = OpenFeature.getClient('my-app')

TypeScript

import {EvaluationContext, OpenFeature} from "@openfeature/server-sdk";
import {GoFeatureFlagProvider} from  "@openfeature/go-feature-flag-provider";


// init Open Feature SDK with GO Feature Flag provider
const goFeatureFlagProvider: GoFeatureFlagProvider = new GoFeatureFlagProvider({
endpoint: 'http://localhost:1031/'
});
OpenFeature.setProvider(goFeatureFlagProvider);
const featureFlagClient = OpenFeature.getClient('my-app');

Evaluate your flag

This code block explains how you can create an EvaluationContext and use it to evaluate your flag.

note

In this example, we are evaluating a boolean flag, but other types are also available.

Refer to the Open Feature documentation to know more about it.

JavaScript

// Context of your flag evaluation.
// With GO Feature Flag you MUST have a targetingKey that is a unique identifier of the user.
const userContext = {
  targetingKey: '1d1b9238-2591-4a47-94cf-d2bc080892f1', // user unique identifier (mandatory)
  firstname: 'john',
  lastname: 'doe',
  email: 'john.doe@gofeatureflag.org',
  admin: true, // this field is used in the targeting rule of the flag "flag-only-for-admin"
  // ...
};

const adminFlag = await featureFlagClient.getBooleanValue('flag-only-for-admin', false, userContext);
if (adminFlag) {
   // flag "flag-only-for-admin" is true for the user
} else {
  // flag "flag-only-for-admin" is false for the user
}

TypeScript

// Context of your flag evaluation.
// With GO Feature Flag you MUST have a targetingKey that is a unique identifier of the user.
const userContext: EvaluationContext = {
  targetingKey: '1d1b9238-2591-4a47-94cf-d2bc080892f1', // user unique identifier
  firstname: 'john',
  lastname: 'doe',
  email: 'john.doe@gofeatureflag.org',
  admin: true, // this field is used in the targeting rule of the flag "flag-only-for-admin"
  // ...
};

const adminFlag = await featureFlagClient.getBooleanValue('flag-only-for-admin', false, userContext);
if (adminFlag) {
  // flag "flag-only-for-admin" is true for the user
} else {
  // flag "flag-only-for-admin" is false for the user
}

Contribute to the provider

You can find the source of the provider in the open-feature/js-sdk-contrib repository.