Build a Real-time Stock Tracker

Your Assignment: Real-time Stock/Crypto Tracker

Build a vanilla JavaScript application that displays real-time stock or cryptocurrency prices using a public WebSocket or REST API.

Requirements

1. Real-time Data: Connect to a public API (CoinGecko, Alpha Vantage, or similar) to fetch live price data.
2. Search with Debouncing: Implement a search bar where users can filter stocks/coins. Every keystroke must NOT trigger an API call — implement debouncing.
3. Rate Limiting Handling: What happens when the API blocks you? Implement retry logic with exponential backoff.
4. No Frameworks: Vanilla JS only. No React, Vue, or Angular.
5. Performance: Use DocumentFragment for DOM updates. Implement virtual scrolling if displaying 100+ items.

Evaluation Criteria

• Proper error handling (network failures, API errors)
• Debounce implementation (not from a library)
• Clean separation of concerns (API layer, DOM layer, State layer)
• Rate limit handling with exponential backoff