Build a Voice Agent with JavaScript

1
const { writeFile, appendFile } = require("fs/promises");
2
const { DeepgramClient } = require("@deepgram/sdk");
3
const fetch = require("cross-fetch");
4
const { join } = require("path");
5
6
const deepgram = new DeepgramClient({ apiKey: process.env.DEEPGRAM_API_KEY });
7
8
const agent = async () => {
9
  let audioBuffer = Buffer.alloc(0);
10
  let i = 0;
11
  const url = "https://dpgr.am/spacewalk.wav";
12
  const connection = await deepgram.agent.v1.connect();
13
14
  connection.on("message", async (data) => {
15
    if (data.type === "Welcome") {
16
      console.log("Welcome to the Deepgram Voice Agent!");
17
18
      connection.sendSettings({
19
        type: "Settings",
20
        audio: {
21
          input: {
22
            encoding: "linear16",
23
            sample_rate: 24000,
24
          },
25
          output: {
26
            encoding: "linear16",
27
            sample_rate: 16000,
28
            container: "wav",
29
          },
30
        },
31
        agent: {
32
          language: "en",
33
          listen: {
34
            provider: {
35
              type: "deepgram",
36
              model: "nova-3",
37
            },
38
          },
39
          think: {
40
            provider: {
41
              type: "open_ai",
42
              model: "gpt-4o-mini",
43
            },
44
            prompt: "You are a friendly AI assistant.",
45
          },
46
          speak: {
47
            provider: {
48
              type: "deepgram",
49
              model: "aura-2-thalia-en",
50
            },
51
          },
52
          greeting: "Hello! How can I help you today?",
53
        },
54
      });
55
56
      console.log("Deepgram agent configured!");
57
58
      setInterval(() => {
59
        console.log("Keep alive!");
60
        connection.sendKeepAlive({ type: "KeepAlive" });
61
      }, 5000);
62
63
      fetch(url)
64
        .then((r) => r.body)
65
        .then((res) => {
66
          res.on("readable", () => {
67
            const chunk = res.read();
68
            if (chunk) {
69
              console.log("Sending audio chunk");
70
              connection.sendMedia(chunk);
71
            }
72
          });
73
        });
74
    } else if (data.type === "ConversationText") {
75
      await appendFile(join(__dirname, `chatlog.txt`), JSON.stringify(data) + "\n");
76
    } else if (data.type === "UserStartedSpeaking") {
77
      if (audioBuffer.length) {
78
        console.log("Interrupting agent.");
79
        audioBuffer = Buffer.alloc(0);
80
      }
81
    } else if (typeof Blob !== "undefined" && data instanceof Blob) {
82
      console.log("Audio chunk received");
83
      const chunk = Buffer.from(await data.arrayBuffer());
84
      audioBuffer = Buffer.concat([audioBuffer, chunk]);
85
    } else if (data.type === "AgentAudioDone") {
86
      console.log("Agent audio done");
87
      await writeFile(join(__dirname, `output-${i}.wav`), audioBuffer);
88
      audioBuffer = Buffer.alloc(0);
89
      i++;
90
    }
91
  });
92
93
  connection.on("open", () => {
94
    console.log("Connection opened");
95
  });
96
97
  connection.on("close", () => {
98
    console.log("Connection closed");
99
    process.exit(0);
100
  });
101
102
  connection.on("error", (err) => {
103
    console.error("Error:", err.message);
104
  });
105
106
  connection.connect();
107
  await connection.waitForOpen();
108
};
109
110
void agent();