Node.js GPT Chat

A pretty simple Node.js terminal app that uses the GPT API to generate conversations based on user input.

Getting Started

1. Clone the repo and run npm install to install the dependencies.
2. Login into OpenAI platform and get your API Key -> https://platform.openai.com/account/api-keys
3. Create a ´.env´ file in the root of the project and add your API Key as follows:

OPENAI_API_KEY=<YOUR_API_KEY>
OPENAI_ORG_ID= <organization id is optional>

4. Run npm start to start the app.

Customizing the conversation

The way GPT works is by completing a series of messages. These messages are stored in an array called Conversation. We need to persist this array during the lifetime of the app.

The message item must have two attributes: role and content. The role can be user, assistant or system. The content is the actual message as string.

const conversation = [
    {role: 'user', content: 'Hello'},
    {role: 'assistant', content: 'Greetings. Is there something I can assist you with?'},
    {role: 'user', content: 'I want to buy a car'},
    {role: 'assistant', content: 'Sure. What kind of car are you looking for?'},
    // and so on...
];

Also, GPT models uses an initial prompt to generate the conversation with some context or parameters before the actual conversation. This is called a System Prompt (that's right the 3rd role)

For example, if i want to chat with Darth Vader from Star Wars i can set a system prompt like this:

const conversation = [
    {role: 'system', 
     content: 'You are Darth Vader from Star Wars and always order to search for the rebel base.'
    }

This will likely result on messages like these:

You: Hello

GPT: Greetings. Is there something I can assist you with? Perhaps an order to locate 
the rebel base? As you know, we need to locate their hidden location and put an end 
to their efforts to overthrow the galactic empire.

You: I'm searching for Luke Skywalker

GPT: Greetings. I am Darth Vader, Dark Lord of the Sith. While it is true that we seek 
information on the location of the Rebel base, Luke Skywalker has not been our primary 
focus. However, if you have any information regarding his whereabouts or his recent 
activity with the Rebel Alliance, I urge you to share it with me immediately. 
Skywalker poses a major threat to our efforts to restore order throughout 
the Empire, and we must do everything in our power to locate and capture him.".

We can also play with two other parameters: Temperature and Max Tokens. Temperature is a value between 0 and 2 that controls the randomness of the generated text. Max Tokens can be used to limit the length of the generated text.

You can also set which model to use in the conversation. (GPT-3, GPT-4 or its variants)

These parameters are set when creating the ChatCompletion object (./services/gpt.js):

const response = await openai.createChatCompletion({
    model: "gpt-3.5-turbo-0301",
    messages: conversation,  // Here's our conversation array
    temperature: 1.5,
    max_tokens: 100,
 });

Enjoy!

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Created with love ❤️ by Johannstark in Colombia 🇨🇴