> ## 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.
# NodeJS Application Overview
> This guide covers Node.js setup, testing, and running a simple application, along with integrating it into a GitHub Actions workflow.
In this guide, you’ll learn what Node.js is and how to set up, test, and run a simple “Hello World” application. We’ll also show you how to integrate this Node.js project into a custom [GitHub Actions](https://docs.github.com/en/actions) workflow for continuous integration.
## What Is Node.js?
Node.js is an open-source, cross-platform JavaScript runtime built on Chrome’s [V8 engine](https://v8.dev). It enables you to run JavaScript on the server side, unifying your front-end and back-end development in a single language. Installing Node.js also provides npm (Node Package Manager) for managing your dependencies.
* High performance with non-blocking I/O
* Vast ecosystem via `npm`
* Single language for client and server
## Prerequisites
Before you begin, ensure you have Node.js and npm installed on your machine.
```bash theme={null}
node -v # e.g., v18.16.0
npm -v # e.g., 9.8.1
```
Always verify that your CI/CD environment (like GitHub Actions) uses the same Node.js version as your local setup to avoid inconsistencies.
## Sample Project Structure
Below is a minimal Node.js project that returns “Hello World” from a `/hello` endpoint.
| File | Purpose |
| ------------ | -------------------------------------------------------------- |
| package.json | Metadata (name, version), dependencies, and script definitions |
| index.js | Main application file (defines server and routes) |
| test.js | Simple test suite to verify the logic in `index.js` |
## Installing Dependencies
Install all required packages listed in `package.json`:
```bash theme={null}
npm install
```
On success, npm generates a `node_modules` directory containing your project’s dependencies.
## Running Your Tests
Run the test suite defined in `test.js`:
```bash theme={null}
npm test
```
Expected output:
```bash theme={null}
> my-app@1.0.0 test
> node test.js
Testing is successful
```
## Starting the Application
Launch the server:
```bash theme={null}
npm start
```
You’ll see:
```bash theme={null}
> my-app@1.0.0 start
> node index.js
App listening on port 3000
```
In another terminal or your browser, request the `/hello` endpoint:
```bash theme={null}
curl http://localhost:3000/hello
# Hello World!
```
## GitHub Actions Workflow
Automate your CI/CD pipeline by adding a workflow file at `.github/workflows/ci.yml`:
```yaml theme={null}
name: Node.js CI
on: [push, pull_request]
jobs:
build-and-test:
runs-on: ubuntu-latest
strategy:
matrix:
node-version: [18.x]
steps:
- uses: actions/checkout@v3
- name: Use Node.js ${{ matrix.node-version }}
uses: actions/setup-node@v3
with:
node-version: ${{ matrix.node-version }}
- name: Install dependencies
run: npm install
- name: Run tests
run: npm test
- name: Start application
run: npm start
```
## Links and References
* [Node.js Official Website](https://nodejs.org/)
* [npm Documentation](https://docs.npmjs.com/)
* [GitHub Actions](https://docs.github.com/en/actions)
* [V8 JavaScript Engine](https://v8.dev/)