FeatureFlagClient class

Package:
@azure/app-configuration

Client for managing feature flags through the dedicated feature flag endpoint of the Azure App Configuration service.

This requires the 2026-05-01-preview API version or later.

Constructors

FeatureFlagClient(string, FeatureFlagClientOptions)

Initializes a new instance of the FeatureFlagClient class.
FeatureFlagClient(string, TokenCredential, FeatureFlagClientOptions)

Initializes a new instance of the FeatureFlagClient class using a TokenCredential.

Methods

addFeatureFlag(FeatureFlagParam, AddFeatureFlagOptions)

Adds a feature flag through the dedicated feature flag endpoint, failing if the feature flag already exists.

Example usage:

import { DefaultAzureCredential } from "@azure/identity";
import { FeatureFlagClient } from "@azure/app-configuration";

const endpoint = "https://example.azconfig.io";
const credential = new DefaultAzureCredential();
const client = new FeatureFlagClient(endpoint, credential);

const result = await client.addFeatureFlag({
  name: "MyFeatureFlag",
  enabled: true,
});
console.log(`Feature flag ${result.name} is enabled: ${result.enabled}`);
deleteFeatureFlag(FeatureFlagId, DeleteFeatureFlagOptions)

Delete a feature flag through the dedicated feature flag endpoint.

Example usage:

import { DefaultAzureCredential } from "@azure/identity";
import { FeatureFlagClient } from "@azure/app-configuration";

const endpoint = "https://example.azconfig.io";
const credential = new DefaultAzureCredential();
const client = new FeatureFlagClient(endpoint, credential);

await client.deleteFeatureFlag({ name: "MyFeatureFlag" });
getFeatureFlag(FeatureFlagId, GetFeatureFlagOptions)

Get a feature flag through the dedicated feature flag endpoint.

Example usage:

import { DefaultAzureCredential } from "@azure/identity";
import { FeatureFlagClient } from "@azure/app-configuration";

const endpoint = "https://example.azconfig.io";
const credential = new DefaultAzureCredential();
const client = new FeatureFlagClient(endpoint, credential);

const featureFlag = await client.getFeatureFlag({ name: "MyFeatureFlag" });
console.log(`Feature flag ${featureFlag.name} is enabled: ${featureFlag.enabled}`);
listFeatureFlagRevisions(ListFeatureFlagRevisionsOptions)

List revisions of a feature flag through the dedicated feature flag endpoint.

Example usage:

import { DefaultAzureCredential } from "@azure/identity";
import { FeatureFlagClient } from "@azure/app-configuration";

const endpoint = "https://example.azconfig.io";
const credential = new DefaultAzureCredential();
const client = new FeatureFlagClient(endpoint, credential);

for await (const featureFlag of client.listFeatureFlagRevisions({
  nameFilter: "MyFeatureFlag",
})) {
  console.log(`Revision last modified: ${featureFlag.lastModified}`);
}
listFeatureFlags(ListFeatureFlagsOptions)

List feature flags through the dedicated feature flag endpoint.

Example usage:

import { DefaultAzureCredential } from "@azure/identity";
import { FeatureFlagClient } from "@azure/app-configuration";

const endpoint = "https://example.azconfig.io";
const credential = new DefaultAzureCredential();
const client = new FeatureFlagClient(endpoint, credential);

for await (const featureFlag of client.listFeatureFlags()) {
  console.log(`Feature flag: ${featureFlag.name}`);
}

To conditionally retrieve pages, pass a pageEtags array (one etag per page). Each etag is sent as an If-None-Match header, and unchanged pages are returned as empty pages with their etag preserved, mirroring AppConfigurationClient.listConfigurationSettings.
listLabels(ListLabelsOptions)

List the labels used by feature flags through the dedicated feature flag endpoint.

Example usage:

import { DefaultAzureCredential } from "@azure/identity";
import { FeatureFlagClient } from "@azure/app-configuration";

const endpoint = "https://example.azconfig.io";
const credential = new DefaultAzureCredential();
const client = new FeatureFlagClient(endpoint, credential);

for await (const label of client.listLabels()) {
  console.log(`Found label: ${label.name}`);
}
setFeatureFlag(FeatureFlagParam, SetFeatureFlagOptions)

Adds or updates a feature flag through the dedicated feature flag endpoint.

Example usage:

import { DefaultAzureCredential } from "@azure/identity";
import { FeatureFlagClient } from "@azure/app-configuration";

const endpoint = "https://example.azconfig.io";
const credential = new DefaultAzureCredential();
const client = new FeatureFlagClient(endpoint, credential);

const result = await client.setFeatureFlag({
  name: "MyFeatureFlag",
  enabled: true,
});
console.log(`Feature flag ${result.name} is enabled: ${result.enabled}`);

Constructor Details

FeatureFlagClient(string, FeatureFlagClientOptions)

Initializes a new instance of the FeatureFlagClient class.

new FeatureFlagClient(connectionString: string, options?: FeatureFlagClientOptions)

Parameters

connectionString

string

The connection string of the App Configuration service.

options
FeatureFlagClientOptions

Options for the FeatureFlagClient.

FeatureFlagClient(string, TokenCredential, FeatureFlagClientOptions)

Initializes a new instance of the FeatureFlagClient class using a TokenCredential.

new FeatureFlagClient(endpoint: string, tokenCredential: TokenCredential, options?: FeatureFlagClientOptions)

Parameters

endpoint

string

The endpoint of the App Configuration service (ex: https://sample.azconfig.io).

tokenCredential
TokenCredential

An object that implements the TokenCredential interface used to authenticate requests to the service. Use the @azure/identity package to create a credential that suits your needs.

options
FeatureFlagClientOptions

Options for the FeatureFlagClient.

Method Details

addFeatureFlag(FeatureFlagParam, AddFeatureFlagOptions)

Adds a feature flag through the dedicated feature flag endpoint, failing if the feature flag already exists.

Example usage:

import { DefaultAzureCredential } from "@azure/identity";
import { FeatureFlagClient } from "@azure/app-configuration";

const endpoint = "https://example.azconfig.io";
const credential = new DefaultAzureCredential();
const client = new FeatureFlagClient(endpoint, credential);

const result = await client.addFeatureFlag({
  name: "MyFeatureFlag",
  enabled: true,
});
console.log(`Feature flag ${result.name} is enabled: ${result.enabled}`);

function addFeatureFlag(featureFlag: FeatureFlagParam, options?: AddFeatureFlagOptions): Promise<AddFeatureFlagResponse>

Parameters

featureFlag
FeatureFlagParam

The feature flag to add. Its name and label identify the resource.

options
AddFeatureFlagOptions

Optional parameters for the request.

Returns

Promise<AddFeatureFlagResponse>

deleteFeatureFlag(FeatureFlagId, DeleteFeatureFlagOptions)

Delete a feature flag through the dedicated feature flag endpoint.

Example usage:

import { DefaultAzureCredential } from "@azure/identity";
import { FeatureFlagClient } from "@azure/app-configuration";

const endpoint = "https://example.azconfig.io";
const credential = new DefaultAzureCredential();
const client = new FeatureFlagClient(endpoint, credential);

await client.deleteFeatureFlag({ name: "MyFeatureFlag" });

function deleteFeatureFlag(id: FeatureFlagId, options?: DeleteFeatureFlagOptions): Promise<DeleteFeatureFlagResponse>

Parameters

id
FeatureFlagId

The id of the feature flag to delete.

options
DeleteFeatureFlagOptions

Optional parameters for the request.

Returns

Promise<DeleteFeatureFlagResponse>

getFeatureFlag(FeatureFlagId, GetFeatureFlagOptions)

Get a feature flag through the dedicated feature flag endpoint.

Example usage:

import { DefaultAzureCredential } from "@azure/identity";
import { FeatureFlagClient } from "@azure/app-configuration";

const endpoint = "https://example.azconfig.io";
const credential = new DefaultAzureCredential();
const client = new FeatureFlagClient(endpoint, credential);

const featureFlag = await client.getFeatureFlag({ name: "MyFeatureFlag" });
console.log(`Feature flag ${featureFlag.name} is enabled: ${featureFlag.enabled}`);

function getFeatureFlag(id: FeatureFlagId, options?: GetFeatureFlagOptions): Promise<GetFeatureFlagResponse>

Parameters

id
FeatureFlagId

The id of the feature flag to retrieve.

options
GetFeatureFlagOptions

Optional parameters for the request.

Returns

Promise<GetFeatureFlagResponse>

listFeatureFlagRevisions(ListFeatureFlagRevisionsOptions)

List revisions of a feature flag through the dedicated feature flag endpoint.

Example usage:

import { DefaultAzureCredential } from "@azure/identity";
import { FeatureFlagClient } from "@azure/app-configuration";

const endpoint = "https://example.azconfig.io";
const credential = new DefaultAzureCredential();
const client = new FeatureFlagClient(endpoint, credential);

for await (const featureFlag of client.listFeatureFlagRevisions({
  nameFilter: "MyFeatureFlag",
})) {
  console.log(`Revision last modified: ${featureFlag.lastModified}`);
}

function listFeatureFlagRevisions(options?: ListFeatureFlagRevisionsOptions): PagedAsyncIterableIterator<FeatureFlag, ListFeatureFlagRevisionsPage, PageSettings>

Parameters

options
ListFeatureFlagRevisionsOptions

Optional parameters for the request.

Returns

PagedAsyncIterableIterator<FeatureFlag, ListFeatureFlagRevisionsPage, PageSettings>

listFeatureFlags(ListFeatureFlagsOptions)

List feature flags through the dedicated feature flag endpoint.

Example usage:

import { DefaultAzureCredential } from "@azure/identity";
import { FeatureFlagClient } from "@azure/app-configuration";

const endpoint = "https://example.azconfig.io";
const credential = new DefaultAzureCredential();
const client = new FeatureFlagClient(endpoint, credential);

for await (const featureFlag of client.listFeatureFlags()) {
  console.log(`Feature flag: ${featureFlag.name}`);
}

To conditionally retrieve pages, pass a pageEtags array (one etag per page). Each etag is sent as an If-None-Match header, and unchanged pages are returned as empty pages with their etag preserved, mirroring AppConfigurationClient.listConfigurationSettings.

function listFeatureFlags(options?: ListFeatureFlagsOptions): PagedAsyncIterableIterator<FeatureFlag, ListFeatureFlagPage, PageSettings>

Parameters

options
ListFeatureFlagsOptions

Optional parameters for the request.

Returns

PagedAsyncIterableIterator<FeatureFlag, ListFeatureFlagPage, PageSettings>

listLabels(ListLabelsOptions)

List the labels used by feature flags through the dedicated feature flag endpoint.

Example usage:

import { DefaultAzureCredential } from "@azure/identity";
import { FeatureFlagClient } from "@azure/app-configuration";

const endpoint = "https://example.azconfig.io";
const credential = new DefaultAzureCredential();
const client = new FeatureFlagClient(endpoint, credential);

for await (const label of client.listLabels()) {
  console.log(`Found label: ${label.name}`);
}

function listLabels(options?: ListLabelsOptions): PagedAsyncIterableIterator<SettingLabel, ListLabelsPage, PageSettings>

Parameters

options
ListLabelsOptions

Optional parameters for the request.

Returns

PagedAsyncIterableIterator<SettingLabel, ListLabelsPage, PageSettings>

setFeatureFlag(FeatureFlagParam, SetFeatureFlagOptions)

Adds or updates a feature flag through the dedicated feature flag endpoint.

Example usage:

import { DefaultAzureCredential } from "@azure/identity";
import { FeatureFlagClient } from "@azure/app-configuration";

const endpoint = "https://example.azconfig.io";
const credential = new DefaultAzureCredential();
const client = new FeatureFlagClient(endpoint, credential);

const result = await client.setFeatureFlag({
  name: "MyFeatureFlag",
  enabled: true,
});
console.log(`Feature flag ${result.name} is enabled: ${result.enabled}`);

function setFeatureFlag(featureFlag: FeatureFlagParam, options?: SetFeatureFlagOptions): Promise<SetFeatureFlagResponse>

Parameters

featureFlag
FeatureFlagParam

The feature flag to add or update. Its name and label identify the resource.

options
SetFeatureFlagOptions

Optional parameters for the request.

Returns

Promise<SetFeatureFlagResponse>