Comment by flohofwoe

IIRC Emscripten has removed asm.js support around 2020, and that was probably the most important toolchain that ever supported asm.js (maybe followed by Rust, don't know if they still support it though)

> You can't call most web apis from wasm.

You can't from strict asm.js either, since it only supports numbers (no JS strings or objects) and manages the C heap in an ArrayBuffer object just like WASM.

> But more important for what i was trying to do, you can't zero copy buffers from js to wasm.

Same problem as above, you need to call out into "real" Javascript from asm.js and you can't map other ArrayBuffers directly into the 'asm.js heap' either, a copy is needed. The "Javascript FFI" really isn't much different between asm.js and WASM.