In a way, yes. asm.js was a deliberately limited subset of JS syntax. By adding a "use asm;" statement, you signaled to the JS engine that everything after th

In a way, yes. asm.js was a deliberately limited subset of JS syntax. By adding a "use asm;" statement, you signaled to the JS engine that everything after that was limited to the asm.js subset, allowing it to simplify the parsing logic and use a fast path for loading the code. You would rarely write asm.js syntax by hand, but rather use it as a compiler output format. WebAssembly takes that further by defining a bytecode that the JS engine doesn't even have to parse, but can accept and work with more directly. This speeds up loading time. Also, loosely put, the way it's defined allows the JS engine to execute it faster. WebAssembly is definitely not intended to be written by hand. Languages like C++ and Rust can now compile to WebAssembly, allowing non-JS source code to be run in a browser. (There _is_ a textual representation of the bytecode as well.)