chore: adding hello vercel example app

package.json

@@ -27,6 +27,7 @@
     "packages/sdk/react-native/example",
     "packages/sdk/react-native/contract-tests/entity",
     "packages/sdk/vercel",
+    "packages/sdk/vercel/examples/hello-vercel",
     "packages/sdk/svelte",
     "packages/sdk/svelte/example",
     "packages/sdk/akamai-base",

packages/sdk/react/examples/vercel-edge/package.json

@@ -1,5 +1,5 @@
 {
-  "name": "@internal/react-sdk-example-vercel-edge",
+  "name": "@launchdarkly/react-sdk-example-vercel-edge",
   "private": true,
   "scripts": {
     "dev": "next dev",

packages/sdk/vercel/examples/hello-vercel/.env.example

@@ -0,0 +1,3 @@
+LD_CLIENT_SIDE_ID=
+VERCEL_EDGE_CONFIG=
+LAUNCHDARKLY_FLAG_KEY=sample-feature

packages/sdk/vercel/examples/hello-vercel/.gitignore

@@ -0,0 +1,4 @@
+node_modules
+dist
+.env*
+!.env.example

packages/sdk/vercel/examples/hello-vercel/README.md

@@ -0,0 +1,51 @@
+# LaunchDarkly sample Vercel application
+
+We've built a simple console application that demonstrates how the LaunchDarkly Vercel server SDK works.
+The app evaluates feature flags using data stored in
+[Vercel Edge Config](https://vercel.com/docs/edge-config/overview).
+
+Below, you'll find the build procedure. For more comprehensive instructions, you can visit your
+[Quickstart page](https://app.launchdarkly.com/quickstart#/) or the
+[Vercel SDK reference guide](https://docs.launchdarkly.com/sdk/server-side/vercel).
+
+## Prerequisites
+
+This example requires the [LaunchDarkly Vercel integration](https://vercel.com/integrations/launchdarkly)
+to be configured. The integration syncs your LaunchDarkly flag data to Vercel Edge Config so that
+the Vercel SDK can read it without connecting to LaunchDarkly servers.
+
+## Build instructions
+
+1. Set the `VERCEL_EDGE_CONFIG` environment variable to your Vercel Edge Config connection string.
+   You can find this in your Vercel project settings under Edge Config.
+
+   ```bash
+   export VERCEL_EDGE_CONFIG="https://edge-config.vercel.com/ecfg_..."
+   ```
+
+2. Set the `LD_CLIENT_SIDE_ID` environment variable to your LaunchDarkly client-side ID.
+   The Vercel SDK uses this to look up flag data in Edge Config.
+
+   ```bash
+   export LD_CLIENT_SIDE_ID="my-client-side-id"
+   ```
+
+3. If there is an existing boolean feature flag in your LaunchDarkly project that you want to
+   evaluate, set `LAUNCHDARKLY_FLAG_KEY`:
+
+   ```bash
+   export LAUNCHDARKLY_FLAG_KEY="my-flag-key"
+   ```
+
+   Otherwise, `sample-feature` will be used by default.
+
+4. On the command line, run `yarn start`:
+
+   ```bash
+   yarn start
+   ```
+
+   You should receive the message:
+   > "The sample-feature feature flag evaluates to true."
+
+The application will run continuously and react to the flag changes in LaunchDarkly.

packages/sdk/vercel/examples/hello-vercel/package.json

@@ -0,0 +1,18 @@
+{
+  "name": "@launchdarkly/hello-vercel",
+  "private": true,
+  "version": "1.0.0",
+  "type": "commonjs",
+  "scripts": {
+    "build": "tsc",
+    "start": "yarn build && node ./dist/index.js"
+  },
+  "dependencies": {
+    "@launchdarkly/vercel-server-sdk": "1.3.43",
+    "@vercel/edge-config": "^1.1.0"
+  },
+  "devDependencies": {
+    "@types/node": "^20",
+    "typescript": "^5"
+  }
+}

packages/sdk/vercel/examples/hello-vercel/src/index.ts

@@ -0,0 +1,81 @@
+/* eslint-disable no-console */
+import { createClient } from '@vercel/edge-config';
+
+import { init } from '@launchdarkly/vercel-server-sdk';
+
+const clientSideId = process.env.LD_CLIENT_SIDE_ID;
+const edgeConfig = process.env.VERCEL_EDGE_CONFIG;
+
+// Set flagKey to the feature flag key you want to evaluate.
+const flagKey = process.env.LAUNCHDARKLY_FLAG_KEY || 'sample-feature';
+
+// Set up the evaluation context. This context should appear on your
+// LaunchDarkly contexts dashboard soon after you run the demo.
+const context = { kind: 'user' as const, key: 'example-user-key', name: 'Sandy' };
+
+const ASCII_ART = `
+        ██
+          ██
+      ████████
+         ███████
+██ LAUNCHDARKLY █
+         ███████
+      ████████
+          ██
+        ██
+`;
+
+if (!clientSideId) {
+  console.error(
+    'LaunchDarkly client-side ID is required: set the LD_CLIENT_SIDE_ID environment variable and try again.',
+  );
+  process.exit(1);
+}
+
+if (!edgeConfig) {
+  console.error(
+    'Vercel Edge Config is required: set the VERCEL_EDGE_CONFIG environment variable and try again.',
+  );
+  process.exit(1);
+}
+
+const edgeConfigClient = createClient(edgeConfig);
+const ldClient = init(clientSideId, edgeConfigClient);
+
+async function main() {
+  try {
+    await ldClient.waitForInitialization();
+    console.log('*** SDK successfully initialized!');
+  } catch {
+    console.error(
+      '*** SDK failed to initialize. Please check your Edge Config connection and LaunchDarkly client-side ID for any issues.',
+    );
+    process.exit(1);
+  }
+
+  let previousValue: boolean | undefined;
+
+  const evaluate = async () => {
+    const flagValue = await ldClient.boolVariation(flagKey, context, false);
+
+    if (flagValue !== previousValue) {
+      console.log(`\n*** The ${flagKey} feature flag evaluates to ${flagValue}.`);
+
+      if (flagValue) {
+        console.log(ASCII_ART);
+      }
+
+      previousValue = flagValue;
+    }
+  };
+
+  await evaluate();
+
+  // In CI mode, evaluate once and exit. Otherwise, poll every second to pick
+  // up flag changes — the "run continuously" behavior required by the spec.
+  if (!process.env.CI) {
+    setInterval(() => evaluate().catch(console.error), 1000);
+  }
+}
+
+main().catch(console.error);

packages/sdk/vercel/examples/hello-vercel/tsconfig.json

@@ -0,0 +1,16 @@
+{
+  "compilerOptions": {
+    "target": "ES2022",
+    "module": "CommonJS",
+    "moduleResolution": "Node",
+    "outDir": "dist",
+    "noEmit": false,
+    "strict": true,
+    "esModuleInterop": true,
+    "skipLibCheck": true,
+    "forceConsistentCasingInFileNames": true,
+    "resolveJsonModule": true
+  },
+  "include": ["src"],
+  "exclude": ["dist", "node_modules"]
+}

release-please-config.json

@@ -177,6 +177,11 @@
           "type": "json",
           "path": "/packages/sdk/react/examples/vercel-edge/package.json",
           "jsonpath": "$.dependencies['@launchdarkly/vercel-server-sdk']"
+        },
+        {
+          "type": "json",
+          "path": "/packages/sdk/vercel/examples/hello-vercel/package.json",
+          "jsonpath": "$.dependencies['@launchdarkly/vercel-server-sdk']"
         }
       ]
     },