flare-flags

A lightweight feature flag library for TypeScript with user targeting, cohorts, and React integration. Designed for Cloudflare Workers.

Installation

``bash
bun add flare-flags
`

Quick Start

$3

`typescript
import { FlareFlags } from "flare-flags";

const ff = new FlareFlags({
newFeature: false,
betaFeature: false,
});

// Set configuration
ff.setConfig({
cohorts: {
beta: ["user123"],
premium: [{ plan: "premium" }],
},
flags: {
newFeature: [true], // Enabled for everyone
betaFeature: [false, "user123", "__cohort__premium"], // Enabled for specific users/cohorts
},
});

// Identify user
ff.identify("user123", { plan: "premium" });

// Check flag
if (ff.isEnabled("betaFeature")) {
// Show feature
}
`

$3

`tsx
import { createIsFeatureEnabledHook } from "flare-flags/react";
import { FlareFlags } from "flare-flags";

const ff = new FlareFlags({ newFeature: false });
ff.setConfig(config);
const useIsEnabled = createIsFeatureEnabledHook(ff);

function MyComponent() {
const isEnabled = useIsEnabled("newFeature");
return isEnabled ? : null;
}
`

$3

`typescript
import { getConfig, setConfig } from "flare-flags/worker";

const config = await getConfig(env.FLAGS);
await setConfig(env.FLAGS, newConfig);
`

Configuration

Each flag is a tuple: [enabled: boolean, ...matchers]

- [true] - Enabled for everyone
- [false, "user123"] - Enabled for user ID
- [false, { plan: "premium" }] - Enabled for users matching properties
- [false, "__cohort__beta"] - Enabled for cohort members
- [false, "user123", { plan: "premium" }, "__cohort__beta"] - OR logic (any matcher)

`typescript
{
cohorts: {
beta: ["user123", "user456"],
premium: [{ plan: "premium" }],
},
flags: {
publicFeature: [true],
betaFeature: [false, "user123", "__cohort__beta"],
premiumFeature: [false, { plan: "premium" }],
},
}
`

API

$3

`typescript
const ff = new FlareFlags(defaults: Record);
ff.setConfig(config: Config);
ff.identify(id: string, properties?: Record);
ff.isEnabled(flag: string): boolean;
ff.subscribe(listener: () => void): () => void;
ff.reset();
`

$3

`typescript
const useIsEnabled = createIsFeatureEnabledHook(ff);
const isEnabled = useIsEnabled("flagName"); // Inside React component
``

License

MIT