WebAssembly in Action

Appendix B. ccall, cwrap, and direct function calls

This appendix covers

• Calling a module’s function from JavaScript using the Emscripten helper functions ccall and cwrap
• Calling a module’s function directly from JavaScript without using the Emscripten helper functions
• Passing arrays to a function

When working with Emscripten’s generated JavaScript plumbing code, you have a few options for calling into a module. The most common approach is to use the ccall and cwrap functions, which help with memory management when passing and returning strings, for example. You can also call a module function directly.