---
title: "Quickstart: Node, Bun and Deno"
description: "Create a flag and an SDK key, and evaluate the flag in a backend with OpenFeature."
---

> Documentation Index
> Fetch the complete documentation index at: https://docs.ezghcloud.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Quickstart: Node, Bun and Deno

This quickstart creates an environment, a flag and a server key, then evaluates the flag from a
script with OpenFeature and EZGH's server provider.

## Before you start

- **Node.js 20 or later**, Bun or Deno.
- **The `ezgh` CLI** ([install it](/cli/install)), logged in, with a project selected
  (`--project` or `EZGH_PROJECT`), and `FlagsFullAccess` on it (or the root user).

## 1. Create an environment, a flag and a key

```sh
ezgh flags envs create production
ezgh flags create new-checkout --name "New checkout"
ezgh flags toggle new-checkout --env production --on
export EZGH_FLAGS_SDK_KEY=$(ezgh flags keys create --env production --kind server --name quickstart)
```

The flag is a boolean: on, with no rules, it serves `true` to everyone (its default rule). The
key is printed once.

## 2. Install

The provider isn't published to npm yet: install it from GitHub by tag, with OpenFeature's server
SDK.

```sh
npm install @openfeature/server-sdk github:ezgamehost/flags-provider-ts#v0.1.0
```

## 3. Evaluate

```ts title="flags.ts"
import { OpenFeature } from "@openfeature/server-sdk"
import { EzghProvider } from "@ezgh/flags-openfeature/server"

await OpenFeature.setProviderAndWait(new EzghProvider({ sdkKey: process.env.EZGH_FLAGS_SDK_KEY! }))
const flags = OpenFeature.getClient()

const details = await flags.getBooleanDetails("new-checkout", false, { targetingKey: "user-1842", plan: "free" })
console.log(details.value, details.reason)
```

Run it with `node flags.ts` (Node 22.18 or later), `bun flags.ts` or `deno run -A flags.ts`. It
prints `true STATIC`.

## 4. Change the targeting

Keep the new checkout from the free plan, then evaluate again:

```sh
ezgh flags config get new-checkout --env production > checkout.json
```

Add a rule to `checkout.json`'s `rules`:

```json
{ "id": "0199a3c2-7a10-7c11-9b01-1f2e3d4c5b6a", "description": "Free plan", "clauses": [{ "attribute": "plan", "operator": "in", "values": ["free"] }], "serve": { "variation": "false" } }
```

```sh
ezgh flags config set new-checkout --env production --file checkout.json
```

The script now prints `false TARGETING_MATCH`; a context with another plan still gets `true`
(reason `DEFAULT`). A long-running process gets the change within
seconds, without restarting.

## How the server provider works

- It downloads the environment's flags when it starts, and is ready once they're loaded. Then it
  follows a stream of changes; if the stream fails it reads the flags every 30 seconds while it
  reconnects.
- **Evaluation is local:** no network call per evaluation.
- On a change it emits `PROVIDER_CONFIGURATION_CHANGED` with the keys of the flags that changed.
  While it's disconnected it keeps evaluating the last flags it had and emits `PROVIDER_STALE`.
- `endpoint` overrides `https://flags.ezghcloud.com`. `bootstrapPath` starts it from a file
  written by `ezgh flags export`; with `offline: true` it uses only that file (tests, CI).

```ts
new EzghProvider({ sdkKey, bootstrapPath: "flags.json", offline: true })
```

Source: https://docs.ezghcloud.com/flags/quickstart-node/index.mdx