Andy
2fcc446ea8
* Create LaunchDarkly adapter * Update example to include a LaunchDarkly flag * Add missing env to turbo * Rename to defaultLaunchDarklyAdapter * Add winter sale example for providers * Update winter-sale * Document usage in readme * Allow to set the default value through the adapter * Fix readme * Add default value for adapter * Make argument optional * Add @ts-expect-error * Add a LaunchDarkly adapter (#10) * add ld example * reword * remove winter-sale example * remove defaultValue * use @flags-sdk/launchdarkly * add install steps * add changeset * move @vercel/edge-config to peer deps * add more secrets * spell out name * remove unused env var * rename properties * Capitalize * Change import * Fix more imports * expose ldClient * move peerDeps to real deps * clarify Edge Config requirement in README * remove adapter-launchdarkly snippet * upgrade next@canary * polish @flags-sdk/launchdarkly README --------- Co-authored-by: Dominik Ferber <dominik.ferber@gmail.com>
Flags SDK
The feature flags toolkit for Next.js and SvelteKit.
From the creators of Next.js, the Flags SDK is a free open-source library that gives you the tools you need to use feature flags in Next.js and SvelteKit applications.
- Works with any flag provider, custom setups or no flag provider at all
- Compatible with App Router, Pages Router, and Edge Middleware
- Built for feature flags and experimentation
See flags-sdk.dev for full docs and examples.
Installation
Install the package using your package manager:
npm install flags
Setup
Create an environment variable called FLAGS_SECRET.
The FLAGS_SECRET value must have a specific length (32 random bytes encoded in base64) to work as an encryption key. Create one using node:
node -e "console.log(crypto.randomBytes(32).toString('base64url'))"
This secret is required to use the SDK. It is used to read overrides and to encrypt flag values in case they are sent to the client and should stay secret.
Usage
Create a file called flags.ts in your project and declare your first feature flag there:
// app/flags.tsx
import { flag } from 'flags/next';
export const exampleFlag = flag<boolean>({
key: 'example-flag',
decide() {
return true;
},
});
Call your feature flag in a React Server Component:
// app/page.tsx
import { exampleFlag } from './flags';
export default async function Page() {
const example = await exampleFlag();
return <div>{example ? 'Flag is on' : 'Flag is off'}</div>;
}
Feature Flags can also be called in Edge Middleware and API Routes.
Adapters
The Flags SDK has adapters for popular feature flag providers including LaunchDarkly, Optimizely, and Statsig.
Documentation
There is a lot more to the Flags SDK than shown in the example above.
See the full documentation and examples on flags-sdk.dev.