This is an OpenFeature provider implementation for using ConfigCat, a managed feature flag service in JavaScript frontend applications.

$ npm install @openfeature/config-cat-web-provider

The OpenFeature SDK is required as peer dependency.

The minimum required version of @openfeature/web-sdk currently is 1.0.0.

The minimum required version of configcat-js-ssr currently is 8.4.3.

$ npm install @openfeature/web-sdk configcat-js-ssr

The ConfigCat provider uses the ConfigCat JavaScript SSR SDK.

It can be created by passing the ConfigCat SDK options to ConfigCatWebProvider.create. The available options can be found in the ConfigCat JavaScript SSR SDK.

The ConfigCat Web Provider only supports the AutoPolling mode because it caches all evaluation data to support synchronous evaluation of feature flags.

import { OpenFeature } from "@openfeature/web-sdk";
import { ConfigCatWebProvider } from '@openfeature/config-cat-web-provider';

// Create and set the provider.
const provider = ConfigCatWebProvider.create('<sdk_key>');
await OpenFeature.setProviderAndWait(provider);

// Create a client instance to evaluate feature flags.
const client = OpenFeature.getClient();

const value = await client.getBooleanValue('isAwesomeFeatureEnabled', false);
console.log(`isAwesomeFeatureEnabled: ${value}`);

// On application shutdown, clean up the OpenFeature provider and the underlying ConfigCat client.
await OpenFeature.clearProviders();

import { OpenFeature } from "@openfeature/web-sdk";
import { ConfigCatWebProvider } from '@openfeature/config-cat-web-provider';
import { createConsoleLogger, LogLevel } from 'configcat-js-ssr';

// Create and set the provider.
const provider = ConfigCatWebProvider.create('<sdk_key>', {
  logger: createConsoleLogger(LogLevel.Info),
  setupHooks: (hooks) => hooks.on('clientReady', () => console.log('Client is ready!')),
});
await OpenFeature.setProviderAndWait(provider);

// ...

The OpenFeature Evaluation Context is mapped to the ConfigCat User Object.

The ConfigCat User Object has three predefined attributes, and allows for additional attributes. The following shows how the attributes are mapped:

The custom types are mapped the following way:

The following example shows the conversion between an OpenFeature Evaluation Context and the corresponding ConfigCat User:

{
  "targetingKey": "test",
  "email": "email",
  "country": "country",
  "customString": "customString",
  "customNumber": 1,
  "customBoolean": true,
  "customObject": {
    "prop1": "1",
    "prop2": 2
  },
  "customStringArray": [
    "one",
    "two"
  ],
  "customArray": [
    1,
    "2",
    false
  ]
}

{
  "identifier": "test",
  "email": "email",
  "country": "country",
  "custom": {
    "customString": "customString",
    "customBoolean": "true",
    "customNumber": 1,
    "customObject": "{\"prop1\":\"1\",\"prop2\":2}",
    "customStringArray": [
      "one",
      "two"
    ],
    "customArray": "[1,\"2\",false]"
  }
}

The ConfigCat provider emits the following OpenFeature events:

• PROVIDER_READY
• PROVIDER_ERROR
• PROVIDER_CONFIGURATION_CHANGED

Run nx package providers-config-cat-web to build the library.

Run nx test providers-config-cat-web to execute the unit tests via Jest.