> ## Documentation Index
> Fetch the complete documentation index at: https://notes.kodekloud.com/llms.txt
> Use this file to discover all available pages before exploring further.
# Demo WASM in Serverside with NodeJS
> This tutorial teaches how to compile a C program into WebAssembly and execute it in a Node.js environment.
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`
Before you begin, make sure you’ve [installed Node.js](https://nodejs.org/) and set up the [Emscripten SDK](https://emscripten.org/docs/getting_started/downloads.html).\
Run `emcc --version` to verify your installation.
Check your Node.js version:
```bash theme={null}
node -v
# Expected output:
# v14.18.2
```
## 1. Write the C Source
Create a file named `helloworld.c` with the following contents:
```c theme={null}
#include
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:
```bash theme={null}
emcc /path/to/helloworld.c -o /path/to/helloworld.js
```
This command produces:
| File | Description |
| --------------- | ------------------------------------------------------------------- |
| helloworld.js | JavaScript “glue” code that locates, loads, and runs the WASM asset |
| helloworld.wasm | Compiled WebAssembly module |
The top of `helloworld.js` looks like this:
```javascript theme={null}
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:
```bash theme={null}
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](https://nodejs.org/)
* [Emscripten Documentation](https://emscripten.org/docs/)
* [WebAssembly Developer Guide](https://webassembly.org/getting-started/developers-guide/)