C++ in WebAssembly

← Back to Language Index

C++ support for WebAssembly is handled by the C language support. And C language support is currently excellent.

However, specific C++ tools are maturing quickly. For example, Cheerp targets compiling C++ to WebAssembly with generated JavaScript interop.

Read the C language guide for examples and more coverage of the WASI SDK, Clang, LLVM, and Emscripten

Usage

For the most part, C++ support comes via C support. Both Emscripten and the C WASI SDK provide support for C++. Recent versions of LLVM and Clang support WebAssembly out of the box.

For this reason, it should be possible to compile C++ code both for browser targets and WASI targets. One thing to be aware of with C++, though, is that exception handling is not yet supported.

Pros and Cons

Things we like:

• Because C is so well supported, C++ is among the better supported WebAssembly languages
• It is great that common compilers have added support
• We believe C++-centered tooling for WebAssembly is on the rise

We’re neutral about:

• Setup is not easy, but it is doable

Things we’re not big fans of:

• Features like exception handling are sorely missed

Examples

See the example on the C page.

Learn More

Here are some great resources:

• The WebAssembly and C++ blog post by Evan Martin is a great analysis of the state of C++ dev for WebAssembly.
• Cheerp is an LLVM-based toolchain for compiling C++ to Wasm and JavaScript. An overview blog post explains the basics.
• Mozilla has a tutorial on Compiling C++ to Wasm with Emscripten
• We love this really cool slide presentation with a code walk of C++ in the browser
• Example of building C++ WebAssembly files with Clang
• The yo-wasm tool can help you get started faster. (Yes, we built yo-wasm.)
• The QT GUI toolkit supports compiling to WebAssembly for the browser. (We blogged about LibreOffice in the browser. That uses QT.)
• An article showing how to use Emscripten to compile C++ to Wasm
• TutorialsPoint has a tutorial for compiling C++ to WebAssembly using Emscripten, but it focuses only on the browser case.