MicroQuickJS
Public repository of the Micro QuickJS Javascript Engine
...The engine is intentionally small in ROM footprint while still providing practical performance comparable to lightweight desktop-grade embeddable engines in its class. To stay small and predictable, it supports a subset of JavaScript close to ES5 rather than modern ECMAScript features, which keeps implementation complexity and runtime overhead lower. It also offers a stricter mode that forbids certain error-prone or inefficient constructs, encouraging safer and more deterministic code in embedded environments.