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How JavaScript Works Behind the Scenes – Execution Context, Call Stack & Event Loop

If you've ever wondered how JavaScript handles your code behind the scenes—especially with functions, asynchronous operations, and callbacks—then this blog is for you. Let’s explore the JavaScript engine's internal workflow and understand how everything from function execution to setTimeout actually works. ⚙️ The JavaScript Engine At the core of your browser lies the JavaScript Engine (like V8 for Chrome, SpiderMonkey for Firefox). It’s responsible for: Parsing your code Compiling it (Just-In-Time compilation) Executing it JavaScript is single-threaded and non-blocking, which is made possible thanks to the Event Loop, Web APIs, and the Callback Queue.

Apr 19, 2025 - 12:48
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How JavaScript Works Behind the Scenes – Execution Context, Call Stack & Event Loop

If you've ever wondered how JavaScript handles your code behind the scenes—especially with functions, asynchronous operations, and callbacks—then this blog is for you.

Let’s explore the JavaScript engine's internal workflow and understand how everything from function execution to setTimeout actually works.

⚙️ The JavaScript Engine

At the core of your browser lies the JavaScript Engine (like V8 for Chrome, SpiderMonkey for Firefox). It’s responsible for:

  • Parsing your code
  • Compiling it (Just-In-Time compilation)
  • Executing it

JavaScript is single-threaded and non-blocking, which is made possible thanks to the Event Loop, Web APIs, and the Callback Queue.

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