Aggregating Stock Market Data: A JavaScript Promises Tutorial

This tutorial builds a market data aggregation service using JavaScript Promises, covering creating promises with resolve and reject, chaining .then() and .catch() for sequential operations, Promise.all for concurrent parallel fetches with shared failure, Promise.allSettled for partial success when some tickers may be unavailable, async/await syntax for sequential async logic with try/catch, and Promise.race combined with a timeout wrapper for bounding slow API responses.