Emscripten is a compiler that allows you to compile code from any LLVM based language to WebAssembly Binary by being tightly coupled with LLVM, Clang, Binaryen, and Closure Compiler.
See https://emscripten.org/docs/getting_started/Tutorial.html#running-emscripten for more detail.
In your shell of choice, navigate to the emsdk directory and run the following commands:
git clone https://github.com/emscripten-core/emsdk.git
./emsdk install latest
./emsdk install activate || ./emsdk install activate --permanent
Run ./emsdk help for more information.
See https://emscripten.org/docs/tools_reference/emsdk.html#command-line-syntax for full emsdk command list.
To start with examples:
Run using VSCode's Live Server or any other server, to serve the HTML file at the root. It contains all examples served from the build folder. Uncomment the script you want to run in the HTML file.
To build from source folders:
Mac / Linux / Windows: bash build.sh
Note: Not all scripts are included. Some may be specific to your OS.
Grab Wasmtime:
Mac / Linux: curl https://wasmtime.dev/install.sh -sSf | bash
Note: If you are using Windows, using Wasmtime to run files requires .msi installation from https://github.com/bytecodealliance/wasmtime/releases.
Note: If you are using Windows, wat2wasm requires the WABT package from https://github.com/WebAssembly/wabt/releases and then ran via cmd. Ensure all path variables are set correctly.
See src/library for all examples.
See src/library/cmake for examples on compiling and including libraries.
Open build/gol.html with VS Code Live Server for an example, or use the build command to build the HTML file from C++ source.
Note: It is recommended to pass optimization flags (O1-O3) and MINIFY_HTML=1 when producing HTML files to reduce the size of the output. Note: No optimization flags used means emcc considers the build to be a debug build.
See index.html, (line 150-164) for example - https://webassembly.github.io/spec/js-api/#sample
Note: -s USE_CLOSURE_COMPILER=1 and optimization flags like -O1, -O2, -O3 can be used further optimize the output, and are recommended.
More information about building WASM standalone using emcc, in relation to V8 - https://v8.dev/blog/emscripten-standalone-wasm
Use wasm-dis or wasm2wat to view the binaries in text format. https://github.com/WebAssembly/binaryen/blob/main/src/tools/wasm-dis.cpp
See /src/js/*.js & Line 134 - 148 in index.html for the example.
See the src/wasi directory for more information on WASI.
Use wat2wasm to convert wat text file to wasm binaries. https://github.com/webassembly/wabt / https://github.com/xtuc/webassemblyjs/tree/master/packages/wast-loader
To see more examples, visit https://github.com/emscripten-core/emscripten/wiki/Porting-Examples-and-Demos