Explore Javascript Engines

[alandefreitas]

https://github.com/lynx-family/primjs (or https://bellard.org/quickjs/ https://github.com/quickjs-ng/quickjs) could be an alternative to duktape. It's more constantly maintained and supports ES2019.

[alandefreitas]

We took a closer look at QuickJS. It’s compact (~370 KB) and supports full ES2023. But it doesn’t play nicely with MSVC.

It needs C11 features like <stdatomic.h> and __int128, which plain cl.exe doesn’t support. So on Windows, users would need Clang with the Visual Studio runtime (per their own support matrix).

If we can work around that with small patches, QuickJS is still a good option. But if we hit a wall, here are other lightweight engines:

Engine Name	GitHub / Homepage	JS Feature Support	Windows / MSVC Support	GCC / Clang Support	Binary Size (Approx)	License
QuickJS	bellard/quickjs	ES2023	No (clang-cl only)	Yes	~370 KB	MIT
PrimJS	lynxkite/primjs	ES2019	No (POSIX only)	Yes	~370 KB	MIT
JerryScript	jerryscript-project/jerryscript	ES5.1 + ES2022 subset	Yes	Yes	~200 KB	Apache 2.0
Escargot	samsung/escargot	ES2025 (large subset)	Yes	Yes	~400–500 KB	LGPL 2.1
MuJS	artifexsoftware/mujs	ES5.1	Yes	Yes	~200–300 KB	ISC
Moddable XS	Moddable-OpenSource/moddable	ES2025 (~99% coverage)	Yes (via SDK tooling)	Yes	~100–300 KB	Apache / GPL / LGPL
mJS	cesanta/mjs	Restricted ES6 subset	Yes	Yes	~50–60 KB	GPL 2.0 / Commercial
Elk	cesanta/elk	Very minimal ES6 subset	Yes	Yes	~20–30 KB	GPL 2.0 / Commercial

[alandefreitas]

For Python-like scripts, we can also consider MicroPython (~300–600 KB) instead of CPython. For the lua scripts, we're fine with the original Lua library.