Why is JavaScript called single-threaded?
Because there is one call stack. Only one statement executes at a time. Async operations like timers and network calls are handled by Web APIs and the event loop, not extra threads.
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More FAQs in How the JavaScript Engine Works Behind the Scenes
It parses source code into an AST, JIT-compiles it to bytecode and machine code, and executes it on a single-threaded call stack while managing memory on a heap.
Just-In-Time compilation means the engine compiles code to machine code at runtime. An interpreter runs first for fast startup, and an optimizing compiler recompiles hot code for speed.
Node.js uses V8, the same JavaScript engine that powers Google Chrome. V8 is written in C++ and developed by Google.
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