JavaScript (Node)

The Hyphen Toggle Provider for Node.js is an OpenFeature provider implementation that enables seamless feature flag evaluation. This section covers setup, usage, and configuration specific to the JavaScript implementation.

Installation

Install the provider and the OpenFeature server SDK:

npm install @openfeature/server-sdk @hyphen/openfeature-server-provider

Setup and Initialization

To begin using the Hyphen Provider, follow these steps:

Import the required modules.
Configure the provider with your publicKey and application options.
Register the provider with OpenFeature.

import { OpenFeature } from '@openfeature/server-sdk';  
import { HyphenProvider, type HyphenProviderOptions } from '@hyphen/openfeature-server-provider';

const publicKey = "your-public-key-here";

const options: HyphenProviderOptions = {  
  application: 'your-application-name',  
  environment: 'production',  
};

await OpenFeature.setProviderAndWait(new HyphenProvider(publicKey, options));

Feature Evaluation

Basic Feature Evaluation

Evaluate a feature flag using default values:

const client = OpenFeature.getClient();

const flagDetails = await client.getBooleanDetails('feature-flag-key', false);

console.log(flagDetails.value); // true or false

Contextual Feature Evaluation

Enhance evaluations by providing user or application context:

const context: HyphenEvaluationContext = {  
  targetingKey: 'user-123',  
  ipAddress: '203.0.113.42',  
  customAttributes: {  
    subscriptionLevel: 'premium',  
    region: 'us-east',  
  },  
  user: {  
    id: 'user-123',  
    email: '[email protected]',  
    name: 'John Doe',  
    customAttributes: {  
      role: 'admin',  
    },  
  },  
};

const flagDetailsWithContext = await client.getBooleanDetails('feature-flag-key', false, context);

console.log(flagDetailsWithContext.value); // true or false

Configuration

Options

Option	Type	Description
`application`	string	The application id or alternate id.
`environment`	string	The environment in which your application is running (e.g., `production`, `staging`).
`enableToggleUsage`	boolean	Enable or disable the logging of toggle usage (telemetry).
`cache`	object	Configuration for caching feature flag evaluations.

Cache Configuration

The cache option accepts the following properties:

Property	Type	Default	Description
`ttlSeconds`	number	300	Time-to-live in seconds for cached flag evaluations.
`generateCacheKeyFn`	Function	-	Custom function to generate cache keys from evaluation context.

Example with cache configuration:

const options: HyphenProviderOptions = {
  application: 'your-application-name',
  environment: 'production',
  cache: {
    ttlSeconds: 600, // 10 minutes
    generateCacheKeyFn: (context: HyphenEvaluationContext) => {
      return `${context.targetingKey}-${context.user?.id}`;
    },
  },
};

Context

Provide an EvaluationContext to pass contextual data for feature evaluation.

Context Fields

Field	Type	Description
`targetingKey`	`string`	The key used for caching the evaluation response.
`ipAddress`	`string`	The IP address of the user making the request.
`customAttributes`	`Record<string, any>`	Custom attributes for additional contextual information.
`user`	`object`	An object containing user-specific information for the evaluation.
`user.id`	`string`	The unique identifier of the user.
`user.email`	`string`	The email address of the user.
`user.name`	`string`	The name of the user.
`user.customAttributes`	`Record<string, any>`	Custom attributes specific to the user.

Example

const context: HyphenEvaluationContext = {  
  targetingKey: 'user-456',  
  customAttributes: {  
    subscriptionLevel: 'premium',  
  },  
};

const flagDetails = await client.getBooleanDetails('enable-discounts', false, context);

if (flagDetails.value) {  
  console.log('Discounts enabled for premium users.');  
} else {  
  console.log('No discounts available.');  
}