Demo: Create a Vite Project with Streaming SDK

In this demo, we will create a basic Vite project that integrates the @heygen/streaming-avatar SDK to showcase interactive avatars.

Setup Vite Project

Create a new Vite project:

npm create vite@latest streaming-avatar-demo -- --template vanilla-ts
cd streaming-avatar-demo

Install dependencies:

npm install @heygen/streaming-avatar livekit-client

Step 2: Create Basic Frontend Structure

Edit index.html to include a video element and buttons for interaction:

<!DOCTYPE html>
<html lang="en" data-theme="light">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <link rel="icon" href="/vite.svg" type="image/svg+xml" />
    <link
      rel="stylesheet"
      href="https://cdn.jsdelivr.net/npm/@picocss/pico@2/css/pico.min.css"
    />
    <title>Interactive Avatar Demo</title>
  </head>

  <body>
    <main
      class="container"
      style="display: flex; flex-direction: column; align-items: center"
    >
      <h1>Interactive Avatar Demo (Vite + TypeScript)</h1>

      <!-- Video Section -->
      <article style="width: fit-content">
        <video id="avatarVideo" autoplay playsinline></video>
      </article>

      <!-- Controls Section -->
      <section>
        <section role="group">
          <button id="startSession">Start Session</button>
          <button id="endSession" disabled>End Session</button>
        </section>

        <section role="group">
          <input
            type="text"
            id="userInput"
            placeholder="Type something to talk to the avatar..."
            aria-label="User input"
          />
          <button id="speakButton" role="button">Speak</button>
        </section>
      </section>
    </main>

    <script type="module" src="/src/main.ts"></script>
  </body>
</html>

Step 3: Implement the Streaming Avatar SDK Logic

Create a main.ts file in the src directory:

import StreamingAvatar, {
  AvatarQuality,
  StreamingEvents,
} from "@heygen/streaming-avatar";

// DOM elements
const videoElement = document.getElementById("avatarVideo") as HTMLVideoElement;
const startButton = document.getElementById(
  "startSession"
) as HTMLButtonElement;
const endButton = document.getElementById("endSession") as HTMLButtonElement;
const speakButton = document.getElementById("speakButton") as HTMLButtonElement;
const userInput = document.getElementById("userInput") as HTMLInputElement;

let avatar: StreamingAvatar | null = null;
let sessionData: any = null;

// Helper function to fetch access token
async function fetchAccessToken(): Promise<string> {
  const apiKey = import.meta.env.VITE_HEYGEN_API_KEY;
  const response = await fetch(
    "https://api.heygen.com/v1/streaming.create_token",
    {
      method: "POST",
      headers: { "x-api-key": apiKey },
    }
  );

  const { data } = await response.json();
  return data.token;
}

// Initialize streaming avatar session
async function initializeAvatarSession() {
  const token = await fetchAccessToken();
  avatar = new StreamingAvatar({ token });

  sessionData = await avatar.createStartAvatar({
    quality: AvatarQuality.High,
    avatarName: "default",
  });

  console.log("Session data:", sessionData);

  // Enable end button and disable start button
  endButton.disabled = false;
  startButton.disabled = true;

  avatar.on(StreamingEvents.STREAM_READY, handleStreamReady);
  avatar.on(StreamingEvents.STREAM_DISCONNECTED, handleStreamDisconnected);
}

// Handle when avatar stream is ready
function handleStreamReady(event: any) {
  if (event.detail && videoElement) {
    videoElement.srcObject = event.detail;
    videoElement.onloadedmetadata = () => {
      videoElement.play().catch(console.error);
    };
  } else {
    console.error("Stream is not available");
  }
}

// Handle stream disconnection
function handleStreamDisconnected() {
  console.log("Stream disconnected");
  if (videoElement) {
    videoElement.srcObject = null;
  }

  // Enable start button and disable end button
  startButton.disabled = false;
  endButton.disabled = true;
}

// End the avatar session
async function terminateAvatarSession() {
  if (!avatar || !sessionData) return;

  await avatar.stopAvatar();
  videoElement.srcObject = null;
  avatar = null;
}

// Handle speaking event
async function handleSpeak() {
  if (avatar && userInput.value) {
    await avatar.speak({
      text: userInput.value,
    });
    userInput.value = ""; // Clear input after speaking
  }
}

// Event listeners for buttons
startButton.addEventListener("click", initializeAvatarSession);
endButton.addEventListener("click", terminateAvatarSession);
speakButton.addEventListener("click", handleSpeak);

Note: Add your HeyGen API key to your .env file in the root of your Vite project:

VITE_HEYGEN_API_KEY=your_api_key_here

Step 4: Run the Project

Start the Vite development server:

npm run dev

Open your browser and navigate to http://localhost:5173 to see the demo in action.

Best Practice

To enhance security and avoid exposing your HeyGen API token in the frontend, move the fetchAccessToken function to a backend service.

Details

Set Up a Backend API Endpoint

Create a backend endpoint (e.g., /api/get-access-token) that handles the token retrieval. This endpoint will securely manage your HeyGen API key and provide the token to your frontend.

Here's a basic example using Express:

Install Express:

npm install express

Create a server file (server.js):

const express = require('express');
const fetch = require('node-fetch');
const app = express();
const port = 3000;

app.get('/api/get-access-token', async (req, res) => {
  try {
    const apiKey = process.env.HEYGEN_API_KEY; // Store your API key in an environment variable
    const response = await fetch('https://api.heygen.com/v1/streaming.create_token', {
      method: 'POST',
      headers: { 'x-api-key': apiKey },
    });

    const { data } = await response.json();
    res.json({ token: data.token });
  } catch (error) {
    res.status(500).json({ error: 'Failed to fetch access token' });
  }
});

app.listen(port, () => {
  console.log(`Server running at http://localhost:${port}`);
});

Update Frontend Code

Modify your main.ts to request the token from the backend endpoint:
```
async function fetchAccessToken(): Promise<string> {
  const response = await fetch('/api/get-access-token');
  const { token } = await response.json();
  return token;
}
```
This ensures your API key remains secure and is not exposed in your frontend code.

Conclusion

You now have a basic Vite TypeScript demo using the Streaming Avatar SDK. You can expand this by adding more features such as handling different events or customizing the avatar interactions.