In this part, we're going to construct a simple web application using our knowledge of JavaScript and wasm modules. We start from the C++ side, creating a simple module that exports a function triple, which triples an input number. This function will then be compiled to a wasm module and used in our web app. Here is the C++ code:

1#include <iostream>
2using namespace std;
3
4extern "C" {
5  int triple(int x) {
6    return x * 3;
7  }
8}
9
10int main() {
11  return 0;
12}

We export the triple function by enclosing it within extern "C" which prevents C++ name mangling and makes it recognizable in the wasm module as is. With this module, we can now offer functionality to the users of our web app that efficiently multiplies a number by three, which provides a foundational step in integrating more complex functionality in future applications.

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#include <iostream>

using namespace std;

​

extern "C" {

  int triple(int x) {

    return x * 3;

  }

}

​

int main() {

  return 0;

}