According to the Emscripten website at https://emscripten.org/:
Emscripten is a toolchain that uses LLVM to transpile code to WebAssembly to run in a web browser at near native speeds.
These are the two ways to install Emscripten:
- Clone the repository, install precompiled binaries
- Clone the repositories, build them
I recommend the first one, as LLVM is very time-consuming to build. It is also recommended to use Linux or macOS. If you are on Windows, you can install the Linux subsystem and use that, or use MinGW compiler. The Visual Studio compiler does not seem to support output targets with the four-letter extensions that Emscripten outputs, namely .wasm and .html.