OpenAI API Complete Guide: Build AI Apps with GPT-4 and Whisper

bash
npm install openai

typescript
import OpenAI from 'openai';

const openai = new OpenAI({
  apiKey: process.env.OPENAI_API_KEY,
});

typescript
const response = await openai.chat.completions.create({
  model: "gpt-4o",
  messages: [
    { role: "system", content: "You are a helpful coding assistant." },
    { role: "user", content: "Explain async/await in JavaScript" }
  ],
  temperature: 0.7,
  max_tokens: 1000,
});

console.log(response.choices[0].message.content);

typescript
const tools = [
  {
    type: "function",
    function: {
      name: "get_weather",
      description: "Get the current weather for a city",
      parameters: {
        type: "object",
        properties: {
          city: { type: "string", description: "City name" },
          units: { type: "string", enum: ["celsius", "fahrenheit"] }
        },
        required: ["city"]
      }
    }
  }
];

const response = await openai.chat.completions.create({
  model: "gpt-4o",
  messages: [{ role: "user", content: "What's the weather in Tokyo?" }],
  tools: tools,
  tool_choice: "auto",
});

// The model will call get_weather with { city: "Tokyo" }
const toolCall = response.choices[0].message.tool_calls[0];
console.log(JSON.parse(toolCall.function.arguments));

typescript
const response = await openai.chat.completions.create({
  model: "gpt-4o",
  messages: [
    {
      role: "user",
      content: [
        { type: "text", text: "What's in this image?" },
        { type: "image_url", image_url: { url: "https://example.com/photo.jpg" } }
      ]
    }
  ],
});

typescript
const response = await openai.chat.completions.create({
  model: "gpt-4o",
  messages: [
    { role: "user", content: "List 3 programming languages with their use cases" }
  ],
  response_format: { type: "json_object" },
});

const data = JSON.parse(response.choices[0].message.content);

typescript
const stream = await openai.chat.completions.create({
  model: "gpt-4o",
  messages: [{ role: "user", content: "Write a poem about coding" }],
  stream: true,
});

for await (const chunk of stream) {
  const content = chunk.choices[0]?.delta?.content || '';
  process.stdout.write(content);
}