Saying goodbye to asm.js | SpiderMonkey JavaScript/WebAssembly Engine
asm.js was Mozilla’s response to the question posed by NaCl and PNaCl: how can the web run code at native speeds?
The idea was clever: pick a strict, statically-typed subset of JavaScript that an engine could recognize on the fly and compile down to native code. We could get performance similar to NaCl/PNaCl and still have code live inside web content and use web API’s (no separate sandbox, IPC, or alternative API’s).
asm.js shipped in Firefox 22 back in 2013 and was a success. It let projects like Unity and Unreal ship C/C++ codebases to the web for the first time, using just standard web technologies. The Epic Citadel demo was ported to the web in just four days. It was a landmark achievement, and a fond memory for the original asm.js team.