Understanding JavaScript Engines: QuickJS, V8, TurboFan, and Integration with libuv

JavaScript is an implementation of the ECMAScript standard defined by ECMA‑39. The article first outlines the history of ECMAScript and lists common JavaScript engines.

It then explains the V8 engine architecture and the TurboFan optimization pipeline, illustrating how type feedback allows TurboFan to generate specialized machine code for frequently called functions. A simple function sum(a, b) { return a + b; } example shows how TurboFan bypasses repeated type checks.

Next, the article introduces QuickJS, a small embeddable JavaScript engine supporting ES2023, including modules, async generators, proxies, BigInt, and optional extensions such as BigDecimal and operator overloading. QuickJS can compile JavaScript to a standalone executable without external dependencies.

The QuickJS source tree is displayed, highlighting key files like quickjs.c , quickjs.h , and the C API headers. Memory management relies on reference counting and cycle detection.

Building QuickJS is straightforward: after cloning the repository, run sudo make sudo make install to obtain the qjs , qjsc , and qjscalc tools. Example commands show how to compile a script into a C byte‑code file and then into an executable.

To extend QuickJS, the article walks through creating a C module that exports a plus function, modifying the Makefile, registering the module in qjsc.c , and testing it with a JavaScript file that imports the module.

Integration with libuv is then covered. libuv is a cross‑platform asynchronous I/O library originally written for Node.js. Its event‑loop core functions (e.g., uv_run ) are shown, and a simple timer example demonstrates basic usage.

Finally, the article combines QuickJS with libuv to provide a JavaScript setTimeout implementation. It presents full C source code that creates a custom QuickJS context, registers the setTimeout function, and runs a JavaScript program that uses promises and timers within the libuv event loop.

Throughout the article, code snippets are kept intact inside <code> tags to preserve their original form.