Demo WASM in Serverside with NodeJS

In this tutorial, you’ll learn how to compile a simple C program into WebAssembly (WASM) using Emscripten and then execute it in a Node.js environment. The workflow mirrors browser-based builds, but outputs a JavaScript “glue” file suitable for server-side execution.

Prerequisites

• Node.js (tested with v14.18.2)
• Emscripten SDK with emcc available in your PATH

Check your Node.js version:

node -v
# Expected output:
# v14.18.2

1. Write the C Source

Create a file named helloworld.c with the following contents:

#include <stdio.h>

int main() {
    printf("Hello World\n");
    return 0;
}

2. Compile to WASM for Node.js

Use Emscripten’s emcc compiler to generate both the WebAssembly binary and the JavaScript loader:

emcc /path/to/helloworld.c -o /path/to/helloworld.js

This command produces:

The top of helloworld.js looks like this:

var Module = typeof Module != 'undefined' ? Module : {};
// …glue code to locate and instantiate helloworld.wasm…

3. Execute the WASM Module in Node.js

Run your generated loader script with Node:

node /path/to/helloworld.js
# Output:
# Hello World

That’s all! You’ve successfully compiled a C program into WASM and executed it on the server with Node.js.

Links and References

• Node.js Official Website
• Emscripten Documentation
• WebAssembly Developer Guide