Art of Node - Deployment & Usage Guide

A practical guide for running the Node.js callback and async examples from the Art of Node tutorial.

1. Prerequisites

• Node.js (v0.10.x or higher, any modern LTS version recommended)
• Git (for cloning the repository)
• Text editor (VS Code, Vim, Nano, or any plain text editor)

Verify Node.js installation:

node --version
npm --version

2. Installation

Clone the repository and navigate to the code examples:

git clone https://github.com/max-mapper/art-of-node.git
cd art-of-node/code

Create the required data file that the examples read from:

echo "1" > number.txt

3. Configuration

The examples require a number.txt file in the code/ directory containing an integer.

File structure:

art-of-node/
└── code/
    ├── 2.js
    ├── 3.js
    ├── 4.js
    └── number.txt    # You must create this

Contents of number.txt:

42

(Any integer value works; the scripts increment this number)

4. Build & Run

No build step is required. Run individual examples directly with Node.js:

Example 2: Async Problem (Undefined Output)

node 2.js

Expected output: undefined Purpose: Demonstrates that console.log executes before the async file read completes.

Example 3: Callback Solution

node 3.js

Expected output: 2 (or whatever number you put in number.txt + 1) Purpose: Shows how to use callbacks to ensure code executes after async operations complete.

Example 4: Callback Chaining

node 4.js

Expected output:

done with one, on to the next
done with one, on to the next
done with one, on to the next

Purpose: Demonstrates sequential async operations using nested callbacks (callback hell pattern).

5. Deployment

This is an educational repository designed for local learning. Deployment options depend on your use case:

Option A: Static Site (for the README/guide)

Deploy the markdown documentation to GitHub Pages or Netlify:

# GitHub Pages is automatic for this repo
# Just enable Pages in repository settings

Option B: Cloud IDE (for running examples)

Import into Glitch or CodeSandbox for browser-based execution:

1. Go to glitch.com
2. Import from GitHub: max-mapper/art-of-node
3. Run node code/3.js in the Glitch terminal

Option C: Containerized (if extending)

Create a Dockerfile for production deployment:

FROM node:18-alpine
WORKDIR /app
COPY code/ ./code/
CMD ["node", "code/3.js"]

6. Troubleshooting

Error: ENOENT: no such file or directory, open './number.txt'

Cause: The number.txt file doesn't exist in the code/ directory. Solution:

cd code
echo "1" > number.txt

Output shows undefined in example 2

Cause: This is expected behavior. The console.log executes before the async fs.readFile completes. Solution: No fix needed. This demonstrates the problem that callbacks solve (see example 3).

Error: parseInt is not a function or NaN output

Cause: number.txt contains non-numeric data or is empty. Solution: Ensure number.txt contains only a valid integer (e.g., 42).

Callback hell confusion in example 4

Issue: Deeply nested callbacks are hard to read. Solution: This example intentionally demonstrates the "callback hell" anti-pattern. For production code, use Promises, async/await, or control flow libraries like async.js.