[FSSDK-12107] refactor build system (#1130)

## Summary
- Replaced the TypeScript Rollup plugin with direct tsc compilation followed by pure bundling and updated outdated build tools.
- Created `examples/typescript` directory with an example typescript project, which is used to check that typescript support is working properly.
- CI Integration: Added `typescript_test` job to GitHub Actions workflow.

Author: raju-opti

.github/workflows/javascript.yml

@@ -26,6 +26,22 @@ jobs:
         npm install
         npm run lint
 
+  typescript_test:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v3
+    - name: Set up Node
+      uses: actions/setup-node@v3
+      with:
+        node-version: 20
+        cache-dependency-path: ./package-lock.json
+        cache: 'npm'
+    - name: Run TypeScript example
+      working-directory: .
+      run: |
+        npm install
+        npm run test-typescript
+
   integration_tests:
     uses: optimizely/javascript-sdk/.github/workflows/integration_test.yml@master
     secrets:

.gitignore

@@ -6,6 +6,7 @@ lerna-debug.log
 
 coverage/
 dist/
+.build/
 
 # user-specific ignores ought to be defined in user's `core.excludesfile`
 .idea/*

examples/typescript/.gitignore

@@ -0,0 +1,5 @@
+node_modules/
+dist/
+*.log
+.DS_Store
+package-lock.json

examples/typescript/README.md

@@ -0,0 +1,66 @@
+# TypeScript Example - Optimizely SDK
+
+This example demonstrates all factory functions from the Optimizely SDK, including static and polling datafile managers.
+
+## Files
+
+- `src/index.ts` - Main example demonstrating all SDK factory functions
+- `datafile.json` - Test datafile with Optimizely configuration
+- `datafile-server.js` - Simple HTTP server for testing polling datafile manager
+
+## Running the Example
+
+### From Project Root (Recommended)
+
+Run from the project root to automatically build the SDK, create a tarball, and run the example:
+```bash
+npm run test-typescript
+```
+
+This will:
+1. Install SDK dependencies
+2. Pack the SDK as a tarball (triggers build via `prepare` script)
+3. Install the tarball in this example
+4. Build and run the TypeScript example
+5. Start the datafile server automatically
+6. Clean up after completion
+
+### Manual Setup
+
+### 1. Start the Datafile Server (for polling manager test)
+
+In a separate terminal, run:
+```bash
+node datafile-server.js
+```
+
+This starts an HTTP server at `http://localhost:8910` that serves the `datafile.json` file. The polling project config manager will fetch updates from this server every 10 seconds.
+
+### 2. Run the Example
+
+```bash
+npm start
+```
+
+## What This Example Demonstrates
+
+1. **createStaticProjectConfigManager** - Creates a config manager with a static datafile
+2. **createInstance** - Creates an Optimizely client instance with the static config manager
+3. **createPollingProjectConfigManager** - Creates a config manager that polls for datafile updates from localhost:8910
+4. **getSendBeaconEventDispatcher** - Gets the SendBeacon event dispatcher (Node.js returns undefined)
+5. **eventDispatcher** - Default event dispatcher
+6. **createForwardingEventProcessor** - Creates an event processor that forwards events immediately
+7. **createBatchEventProcessor** - Creates an event processor that batches events
+8. **createOdpManager** - Creates an Optimizely Data Platform manager
+9. **createVuidManager** - Creates a Visitor Unique ID manager
+
+## Test Datafile
+
+The `datafile.json` contains a complete Optimizely configuration with:
+- 2 feature flags (`flag_1`, `flag_2`)
+- 4 experiments (`exp_1`, `exp_2`, `exp_3`, `exp_4`)
+- 7 typed audiences based on age conditions
+- 2 rollouts with delivery rules
+- 1 integer variable (`integer_variable`)
+
+This datafile is used for testing SDK functionality with realistic configuration.

examples/typescript/datafile-server.js

@@ -0,0 +1,77 @@
+#!/usr/bin/env node
+
+/**
+ * Copyright 2026, Optimizely
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/**
+ * Simple HTTP server to serve the datafile for testing polling project config manager
+ * Runs at http://localhost:PORT
+ */
+
+import http from 'http';
+import fs from 'fs';
+import path from 'path';
+import { fileURLToPath } from 'url';
+import { dirname } from 'path';
+
+const __filename = fileURLToPath(import.meta.url);
+const __dirname = dirname(__filename);
+
+const PORT = 8910;
+const datafilePath = path.join(__dirname, 'datafile.json');
+
+const server = http.createServer((req, res) => {
+  console.log(`[${new Date().toISOString()}] ${req.method} ${req.url}`);
+
+  // Read and serve the datafile
+  fs.readFile(datafilePath, 'utf8', (err, data) => {
+    if (err) {
+      console.error('Error reading datafile:', err);
+      res.writeHead(500, { 'Content-Type': 'application/json' });
+      res.end(JSON.stringify({ error: 'Failed to read datafile' }));
+      return;
+    }
+
+    // Set CORS headers for cross-origin requests
+    res.writeHead(200, {
+      'Content-Type': 'application/json',
+      'Access-Control-Allow-Origin': '*',
+      'Access-Control-Allow-Methods': 'GET, OPTIONS',
+      'Access-Control-Allow-Headers': 'Content-Type'
+    });
+
+    res.end(data);
+  });
+});
+
+server.listen(PORT, () => {
+  console.log(`\n=== Datafile Server Started ===`);
+  console.log(`Server running at http://localhost:${PORT}`);
+  console.log(`Serving datafile from: ${datafilePath}`);
+  console.log(`\nPress Ctrl+C to stop the server\n`);
+});
+
+// Handle graceful shutdown
+const shutdown = () => {
+  console.log('\n\nShutting down datafile server...');
+  server.close(() => {
+    console.log('Server stopped');
+    process.exit(0);
+  });
+};
+
+process.on('SIGINT', shutdown);
+process.on('SIGTERM', shutdown);