In order to utilize JavaScript's functionality in your C/C++ code, you need to add a function definition to the importObj.env argument that gets passed into WebAssembly's instantiation function. You can either define the function outside of the importObj.env or inline. The following code snippet demonstrates each option:

// You can define the function inside of the env object:
const env = {
  // Make sure you prefix the function name with "_"!
  _logValueToConsole: value => {
    console.log(`'The value is ${value}'`);
  }
};

// Or define it outside of env and reference it within env:
const logValueToConsole = value => {
  console.log(`'The value is ${value}'`);
};

const env = {
  _logValueToConsole: logValueToConsole
};

Given the manual memory management and strict typing requirements of C, C++, and Rust, you're limited in what can be passed in and utilized in a Wasm module. JavaScript allows you to easily add, remove, and change the values of properties on an object over the course of code execution. You can even extend the language by adding functions to the prototype of a built-in language feature. C, C++, and Rust are much more restrictive, and it can be difficult to take full advantage of WebAssembly if you're not familiar with these languages.