Quest 1 • Lesson 9
💬 Building a Chatbot
A chatbot is an AI system that can hold conversations with users. In this lesson, you'll build a functional chatbot with memory – it remembers the conversation context and can respond intelligently.
"A good chatbot doesn't just answer – it remembers, understands context, and engages naturally."
🧠 How Chatbots Work
- Intent recognition – understanding what the user wants (rule‑based or ML).
- Dialogue management – tracking the conversation state and deciding the next action.
- Response generation – producing a reply (retrieval from a database or generative AI).
- Memory – storing previous exchanges to maintain context.
🚀 Live Chatbot Demo
Chat with a generative chatbot (using google/flan-t5-base via Hugging Face). It remembers the conversation. Adjust temperature to control creativity.
🤖 Bot is typing...
📘 How the chatbot works
The chatbot sends your message (with conversation history) to a free LLM (google/flan-t5-base) via Hugging Face API. It includes the last 5 exchanges to provide context. Temperature controls creativity.
chatbot_memory.js
// Store conversation history
let conversation = [];
// Add a message to history
function addMessage(role, content) {
conversation.push({ role, content });
// Keep only last 10 exchanges to avoid token limits
if (conversation.length > 20) {
conversation.shift();
}
}
// Build a prompt with history
function buildPrompt() {
return conversation
.map(msg => `${msg.role}: ${msg.content}`)
.join("\n");
}
let conversation = [];
// Add a message to history
function addMessage(role, content) {
conversation.push({ role, content });
// Keep only last 10 exchanges to avoid token limits
if (conversation.length > 20) {
conversation.shift();
}
}
// Build a prompt with history
function buildPrompt() {
return conversation
.map(msg => `${msg.role}: ${msg.content}`)
.join("\n");
}
✨ Challenge: Add a System Prompt
Modify the chatbot to include a system prompt – a fixed instruction that guides the model's behaviour (e.g., "You are a helpful assistant specialised in coding.").
// Add system prompt at the start of conversation
const systemPrompt = "You are a friendly AI assistant specialising in web development.";
// In buildPrompt(), prepend system prompt
const fullPrompt = systemPrompt + "\n" + conversation.map(...).join("\n");
// Then send fullPrompt to the LLM.
const systemPrompt = "You are a friendly AI assistant specialising in web development.";
// In buildPrompt(), prepend system prompt
const fullPrompt = systemPrompt + "\n" + conversation.map(...).join("\n");
// Then send fullPrompt to the LLM.
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