EPISODE 6 – Call Stack & Event Loop

JavaScript is often misunderstood as slow because it is single-threaded. In reality, JavaScript uses a smart execution model powered by the call stack, browser APIs, and the event loop to handle tasks efficiently.

In this video, you will understand:

• JavaScript is single-threaded, but that does not mean it is inefficient or slow.
• The call stack is where all synchronous JavaScript code executes, one task at a time.
• Browser APIs handle asynchronous operations such as timers, network requests, and fetch calls without blocking the main thread.
• The event loop continuously checks whether the call stack is free.
• When the stack is empty, the event loop pushes pending callbacks from the task queue back onto the stack.
• Delays in setTimeout or async tasks happen because the stack is busy, not because JavaScript is laggy.
• This system works like a traffic control mechanism, ensuring smooth execution instead of chaos.

Understanding how the call stack and event loop work helps developers debug timing issues, write efficient asynchronous code, and correctly analyze performance problems.