Is JavaScript written in C?

No, modern JavaScript engines like V8 and JavaScriptCore are written in C++, not C. Historically, the very first engine (SpiderMonkey) was written in C, but it has since been rewritten in C++, Rust, and JavaScript.

Details

A common misconception is that JavaScript is written in C. While C heavily influenced JavaScript's syntax, the engines that actually execute JavaScript code are almost universally written in C++ today.

Google's V8 (used in Chrome and Node.js) and Apple's JavaScriptCore (used in Safari) are both implemented in C++. Mozilla's SpiderMonkey, the original JavaScript engine, was initially written in C by Brendan Eich, but has evolved into a complex codebase of C++, Rust, and JavaScript itself.

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