Haxe Compiler and JavaScript Target: ES2022 Syntax Compatibility

Target Runtime Interoperability

Integrating the Haxe compiler with JavaScript targets requires strict alignment between the emitted syntax and the runtime environment's capabilities. When targeting modern environments, the compiler may utilize ES2022 features to optimize output.

There is uncertainty regarding how the compiler handles the boundary between high-level Haxe abstractions and the specific JavaScript version supported by the target browser. Specifically, the compiler may emit ES2022 syntax without explicit warnings, even when the build configuration suggests a need for broader compatibility.

What mechanisms exist to enforce a maximum JavaScript version limit during compilation? How can a developer verify that the generated code avoids ES2022 features when targeting an ES2020 environment?