Chapter 3. Creating your first WebAssembly module
- An overview of the Emscripten toolkit
- Creating a module using Emscripten and Emscripten’s HTML template
- Feature detection to test if WebAssembly is available
In this chapter, you’ll write some C code and then use the Emscripten toolkit to compile it into a WebAssembly module. This will let us look at three approaches we can use with the toolkit to create WebAssembly modules. Just to give you an idea of what’s possible using the toolkit, some of the items that have been ported to WebAssembly using Emscripten include the Unreal Engine 3, SQLite, and AutoCAD.
The Emscripten toolkit is currently the most mature toolkit available to compile C or C++ code into WebAssembly bytecode. It was originally created to transpile such code into asm.js. When work started on the WebAssembly MVP, Emscripten was chosen because it uses the LLVM compiler, and the WebAssembly working group already had experience with LLVM from its work with Google’s Native Client (PNaCl). Emscripten can still be used to transpile C and C++ code into asm.js, but you’ll be using it to compile the code you write into WebAssembly modules.