WebAssembly in Action

B.1. ccall

The ccall function allows you to call a function in the WebAssembly module and receive the results. This function accepts four parameters:

• A string indicating the name of the function in the module that you want to call. When Emscripten creates a WebAssembly module, it will add an underscore character before the function name. Don’t include the leading underscore character, as the ccall function will include that for you.
• The function’s return type. The following values can be specified:
  • null if the function returns void.
  • 'number' if the function returns an integer, float, or pointer.
  • 'string' if the function returns a char*. This is optional and is here for convenience. If used, the ccall function will handle the memory management ...