Streaming chat

$
curl -X POST https://api.vapi.ai/chat \
>
  -H "Authorization: Bearer YOUR_API_KEY" \
>
  -H "Content-Type: application/json" \
>
  -d '{
>
    "assistantId": "your-assistant-id",
>
    "input": "Explain how to set up API authentication in detail",
>
    "stream": true
>
  }'

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// Example SSE events received:
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data: {"id":"stream_123","path":"chat.output[0].content","delta":"Hello"}
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data: {"id":"stream_123","path":"chat.output[0].content","delta":" there!"}
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data: {"id":"stream_123","path":"chat.output[0].content","delta":" How can"}
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data: {"id":"stream_123","path":"chat.output[0].content","delta":" I help?"}
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// TypeScript interface for SSE events:
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interface SSEEvent {
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  id: string;
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  path: string;
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  delta: string;
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}

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async function streamChatMessage(
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  message: string, 
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  previousChatId?: string
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): Promise<string> {
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  const response = await fetch('https://api.vapi.ai/chat', {
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    method: 'POST',
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    headers: {
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      'Authorization': 'Bearer YOUR_API_KEY',
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      'Content-Type': 'application/json'
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    },
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    body: JSON.stringify({
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      assistantId: 'your-assistant-id',
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      input: message,
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      stream: true,
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      ...(previousChatId && { previousChatId })
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    })
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  });
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  const reader = response.body?.getReader();
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  if (!reader) throw new Error('No reader available');
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  const decoder = new TextDecoder();
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  let fullResponse = '';
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  while (true) {
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    const { done, value } = await reader.read();
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    if (done) break;
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    const chunk = decoder.decode(value);
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    const lines = chunk.split('\n').filter(line => line.trim());
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    for (const line of lines) {
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      if (line.startsWith('data: ')) {
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        const data = JSON.parse(line.slice(6));
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        if (data.path && data.delta) {
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          fullResponse += data.delta;
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          process.stdout.write(data.delta);
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        }
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      }
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    }
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  }
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  return fullResponse;
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}

1
const response = await streamChatMessage("Explain API rate limiting in detail");
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console.log('\nComplete response:', response);

1
async function createStreamingConversation() {
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  let lastChatId: string | undefined;
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  async function sendMessage(input: string): Promise<string> {
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    const response = await fetch('https://api.vapi.ai/chat', {
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      method: 'POST',
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      headers: {
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        'Authorization': 'Bearer YOUR_API_KEY',
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        'Content-Type': 'application/json'
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      },
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      body: JSON.stringify({
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        assistantId: 'your-assistant-id',
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        input: input,
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        stream: true,
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        ...(lastChatId && { previousChatId: lastChatId })
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      })
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    });
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    const reader = response.body?.getReader();
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    if (!reader) throw new Error('No reader available');
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    const decoder = new TextDecoder();
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    let fullContent = '';
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    let currentChatId: string | undefined;
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    while (true) {
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      const { done, value } = await reader.read();
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      if (done) break;
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      const chunk = decoder.decode(value);
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      const lines = chunk.split('\n').filter(line => line.trim());
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      for (const line of lines) {
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        if (line.startsWith('data: ')) {
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          const event = JSON.parse(line.slice(6));
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          if (event.id && !currentChatId) {
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            currentChatId = event.id;
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          }
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          if (event.path && event.delta) {
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            fullContent += event.delta;
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            process.stdout.write(event.delta);
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          }
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        }
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      }
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    }
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    if (currentChatId) {
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      lastChatId = currentChatId;
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    }
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    return fullContent;
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  }
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  return { sendMessage };
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}

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const conversation = await createStreamingConversation();
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await conversation.sendMessage("My name is Alice");
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console.log('\n---');
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await conversation.sendMessage("What's my name?"); // Should remember Alice