Redirect stdin to a Node.js script
📦 GitHub->command line.
✨ The Prompt Phrase
echo "data" | node script.js
💻 Code Preview
📦 All-in-One Code
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Redirect stdin to a Node.js script - Interactive Tutorial</title>
<link href="https://fonts.googleapis.com/css2?family=Poppins:wght@300;400;600;700;900&family=Fira+Code:wght@400;500;600&display=swap" rel="stylesheet">
<style>
:root {
--bg-primary: #0a0e27;
--bg-secondary: #151932;
--bg-card: #1e2139;
--accent-purple: #a855f7;
--accent-blue: #3b82f6;
--accent-green: #10b981;
--accent-red: #ef4444;
--accent-yellow: #f59e0b;
--accent-pink: #ec4899;
--accent-cyan: #06b6d4;
--accent-indigo: #6366f1;
--text-primary: #f8fafc;
--text-secondary: #94a3b8;
--gradient-pipe: linear-gradient(135deg, #06b6d4 0%, #3b82f6 100%);
--gradient-flow: linear-gradient(135deg, #3b82f6 0%, #6366f1 100%);
--shadow: 0 20px 60px rgba(0, 0, 0, 0.3);
}
* {
margin: 0;
padding: 0;
box-sizing: border-box;
}
body {
font-family: 'Poppins', sans-serif;
background: var(--bg-primary);
color: var(--text-primary);
line-height: 1.6;
overflow-x: hidden;
}
.container {
max-width: 1200px;
margin: 0 auto;
padding: 20px;
}
.progress-container {
position: fixed;
top: 0;
left: 0;
width: 100%;
height: 5px;
background: var(--bg-secondary);
z-index: 1000;
}
.progress-bar {
height: 100%;
background: var(--gradient-pipe);
width: 0%;
transition: width 0.3s ease;
}
.hero {
text-align: center;
padding: 100px 20px;
background: var(--gradient-pipe);
position: relative;
overflow: hidden;
border-radius: 0 0 50px 50px;
}
.hero::before {
content: '';
position: absolute;
top: 0;
left: 0;
right: 0;
bottom: 0;
background: url('data:image/svg+xml,<svg width="100" height="100" xmlns="http://www.w3.org/2000/svg"><circle cx="50" cy="50" r="2" fill="white" opacity="0.1"/></svg>');
animation: float 20s linear infinite;
}
@keyframes float {
from { transform: translateY(0); }
to { transform: translateY(-100px); }
}
.hero-content {
position: relative;
z-index: 1;
}
.pipe-icon {
font-size: 5rem;
margin-bottom: 20px;
animation: pipeFlow 3s ease-in-out infinite;
}
@keyframes pipeFlow {
0%, 100% { transform: translateX(0); }
50% { transform: translateX(20px); }
}
.command-display {
display: inline-block;
background: rgba(0, 0, 0, 0.4);
padding: 25px 40px;
border-radius: 15px;
font-family: 'Fira Code', monospace;
font-size: 1.5rem;
margin: 30px 0;
border: 3px solid rgba(255, 255, 255, 0.3);
animation: pulse 2s ease-in-out infinite;
color: white;
font-weight: 600;
}
@keyframes pulse {
0%, 100% { transform: scale(1); }
50% { transform: scale(1.05); }
}
.hero h1 {
font-size: 3.5rem;
font-weight: 900;
margin-bottom: 20px;
color: white;
text-shadow: 2px 2px 4px rgba(0,0,0,0.3);
}
.hero p {
font-size: 1.4rem;
opacity: 0.95;
color: white;
}
.section {
margin: 60px 0;
}
.section-title {
font-size: 2.5rem;
margin-bottom: 30px;
background: var(--gradient-pipe);
-webkit-background-clip: text;
-webkit-text-fill-color: transparent;
background-clip: text;
display: inline-block;
font-weight: 700;
}
.card {
background: var(--bg-card);
border-radius: 20px;
padding: 40px;
margin: 30px 0;
box-shadow: var(--shadow);
border: 1px solid rgba(255, 255, 255, 0.05);
transition: transform 0.3s ease;
}
.card:hover {
transform: translateY(-5px);
}
.code-block {
background: #1e1e1e;
border-radius: 15px;
padding: 25px;
margin: 20px 0;
font-family: 'Fira Code', monospace;
position: relative;
}
.code-header {
display: flex;
justify-content: space-between;
align-items: center;
margin-bottom: 15px;
padding-bottom: 15px;
border-bottom: 1px solid rgba(255, 255, 255, 0.1);
}
.terminal-dots {
display: flex;
gap: 6px;
}
.terminal-dot {
width: 12px;
height: 12px;
border-radius: 50%;
}
.dot-red { background: #ff5f56; }
.dot-yellow { background: #ffbd2e; }
.dot-green { background: #27c93f; }
.copy-btn {
background: var(--accent-purple);
color: white;
border: none;
padding: 8px 16px;
border-radius: 8px;
cursor: pointer;
font-size: 0.9rem;
transition: all 0.3s ease;
}
.copy-btn:hover {
background: var(--accent-blue);
transform: scale(1.05);
}
.copy-btn.copied {
background: var(--accent-green);
}
pre {
margin: 0;
overflow-x: auto;
}
code {
color: #e0e0e0;
font-size: 0.95rem;
line-height: 1.8;
}
.code-comment { color: #6a9955; }
.code-string { color: #ce9178; }
.code-keyword { color: #569cd6; }
.code-pipe { color: #06b6d4; font-weight: 600; }
.code-echo { color: #10b981; font-weight: 600; }
.steps {
counter-reset: step-counter;
}
.step {
background: var(--bg-secondary);
border-radius: 15px;
padding: 30px;
margin: 20px 0;
position: relative;
padding-left: 100px;
transition: all 0.3s ease;
}
.step:hover {
background: var(--bg-card);
transform: translateX(10px);
}
.step::before {
counter-increment: step-counter;
content: counter(step-counter);
position: absolute;
left: 20px;
top: 50%;
transform: translateY(-50%);
width: 60px;
height: 60px;
background: var(--gradient-pipe);
border-radius: 50%;
display: flex;
align-items: center;
justify-content: center;
font-size: 1.8rem;
font-weight: 900;
color: white;
}
.step h3 {
color: var(--accent-cyan);
margin-bottom: 10px;
font-size: 1.5rem;
}
.feature-grid {
display: grid;
grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
gap: 25px;
margin: 30px 0;
}
.feature-card {
background: var(--bg-secondary);
padding: 30px;
border-radius: 15px;
text-align: center;
transition: all 0.3s ease;
border: 2px solid transparent;
}
.feature-card:hover {
border-color: var(--accent-cyan);
transform: translateY(-10px);
}
.feature-icon {
font-size: 3.5rem;
margin-bottom: 15px;
}
.feature-title {
font-weight: 600;
color: var(--accent-cyan);
margin-bottom: 10px;
font-size: 1.3rem;
}
.demo-container {
background: var(--bg-secondary);
border-radius: 20px;
padding: 40px;
margin: 30px 0;
}
.flow-diagram {
display: flex;
justify-content: space-around;
align-items: center;
margin: 30px 0;
flex-wrap: wrap;
gap: 20px;
}
.flow-box {
background: var(--bg-card);
padding: 30px;
border-radius: 15px;
border: 2px solid var(--accent-cyan);
text-align: center;
min-width: 150px;
}
.flow-arrow {
font-size: 3rem;
color: var(--accent-cyan);
animation: arrowPulse 2s ease-in-out infinite;
}
@keyframes arrowPulse {
0%, 100% { transform: scale(1); }
50% { transform: scale(1.2); }
}
.terminal {
background: #1e1e1e;
border-radius: 15px;
padding: 20px;
font-family: 'Fira Code', monospace;
min-height: 250px;
margin: 20px 0;
overflow-y: auto;
max-height: 500px;
}
.terminal-line {
margin: 10px 0;
}
.terminal-prompt {
color: var(--accent-green);
}
.demo-button {
background: var(--gradient-pipe);
color: white;
border: none;
padding: 15px 40px;
border-radius: 50px;
font-size: 1.1rem;
font-weight: 600;
cursor: pointer;
transition: all 0.3s ease;
display: inline-flex;
align-items: center;
gap: 10px;
margin: 10px;
}
.demo-button:hover {
transform: scale(1.05);
box-shadow: 0 10px 30px rgba(6, 182, 212, 0.4);
}
.tabs {
display: flex;
gap: 10px;
margin-bottom: 20px;
flex-wrap: wrap;
}
.tab {
padding: 12px 24px;
background: var(--bg-secondary);
border: none;
border-radius: 10px;
color: var(--text-primary);
cursor: pointer;
transition: all 0.3s ease;
font-size: 1rem;
}
.tab:hover {
background: var(--bg-card);
}
.tab.active {
background: var(--gradient-pipe);
color: white;
}
.tab-content {
display: none;
}
.tab-content.active {
display: block;
}
.accordion-header {
cursor: pointer;
display: flex;
justify-content: space-between;
align-items: center;
padding: 20px;
background: var(--bg-secondary);
border-radius: 12px;
margin: 15px 0;
transition: all 0.3s ease;
}
.accordion-header:hover {
background: var(--bg-card);
}
.accordion-icon {
transition: transform 0.3s ease;
font-size: 1.2rem;
}
.accordion-icon.active {
transform: rotate(180deg);
}
.accordion-content {
max-height: 0;
overflow: hidden;
transition: max-height 0.3s ease;
}
.accordion-content.active {
max-height: 2000px;
}
.accordion-body {
padding: 20px;
background: var(--bg-secondary);
border-radius: 12px;
margin-top: 5px;
}
.tip, .warning, .success, .info {
padding: 20px;
border-radius: 10px;
margin: 20px 0;
}
.tip {
background: rgba(59, 130, 246, 0.1);
border-left: 4px solid var(--accent-blue);
}
.tip::before { content: '💡 '; font-size: 1.5rem; }
.warning {
background: rgba(239, 68, 68, 0.1);
border-left: 4px solid var(--accent-red);
}
.warning::before { content: '⚠️ '; font-size: 1.5rem; }
.success {
background: rgba(16, 185, 129, 0.1);
border-left: 4px solid var(--accent-green);
}
.success::before { content: '✅ '; font-size: 1.5rem; }
.info {
background: rgba(236, 72, 153, 0.1);
border-left: 4px solid var(--accent-pink);
}
.info::before { content: '🔍 '; font-size: 1.5rem; }
.quiz-container {
background: var(--bg-card);
border-radius: 20px;
padding: 40px;
margin: 30px 0;
}
.quiz-question {
margin: 30px 0;
}
.quiz-question h3 {
color: var(--accent-purple);
margin-bottom: 20px;
font-size: 1.3rem;
}
.quiz-options {
display: flex;
flex-direction: column;
gap: 15px;
}
.quiz-option {
background: var(--bg-secondary);
padding: 20px;
border-radius: 12px;
cursor: pointer;
transition: all 0.3s ease;
border: 2px solid transparent;
}
.quiz-option:hover {
border-color: var(--accent-blue);
transform: translateX(10px);
}
.quiz-option.correct {
border-color: var(--accent-green);
background: rgba(16, 185, 129, 0.1);
}
.quiz-option.incorrect {
border-color: var(--accent-red);
background: rgba(239, 68, 68, 0.1);
}
.quiz-feedback {
margin-top: 15px;
padding: 15px;
border-radius: 10px;
display: none;
}
.quiz-feedback.show {
display: block;
}
.quiz-feedback.correct {
background: rgba(16, 185, 129, 0.1);
border-left: 4px solid var(--accent-green);
}
.quiz-feedback.incorrect {
background: rgba(239, 68, 68, 0.1);
border-left: 4px solid var(--accent-red);
}
.cheat-sheet {
background: var(--gradient-pipe);
border-radius: 20px;
padding: 40px;
margin: 30px 0;
color: white;
}
.cheat-grid {
display: grid;
grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
gap: 20px;
margin-top: 30px;
}
.cheat-item {
background: rgba(255, 255, 255, 0.15);
backdrop-filter: blur(10px);
padding: 20px;
border-radius: 15px;
border: 1px solid rgba(255, 255, 255, 0.2);
}
.cheat-item h4 {
color: white;
margin-bottom: 10px;
font-weight: 600;
}
.cheat-item code {
background: rgba(0, 0, 0, 0.3);
padding: 4px 8px;
border-radius: 5px;
font-size: 0.9rem;
color: white;
}
.highlight {
color: var(--accent-yellow);
font-weight: 600;
}
.footer {
text-align: center;
padding: 40px 20px;
background: var(--bg-secondary);
margin-top: 80px;
border-radius: 20px;
}
.footer p {
color: var(--text-secondary);
margin: 10px 0;
}
.badge {
display: inline-block;
padding: 6px 12px;
background: var(--gradient-pipe);
border-radius: 20px;
font-size: 0.85rem;
font-weight: 600;
margin: 5px;
}
.confetti {
position: fixed;
width: 10px;
height: 10px;
background: var(--accent-cyan);
animation: confetti-fall 3s linear forwards;
z-index: 9999;
}
@keyframes confetti-fall {
to {
transform: translateY(100vh) rotate(360deg);
opacity: 0;
}
}
@media (max-width: 768px) {
.hero h1 { font-size: 2rem; }
.command-display { font-size: 1rem; padding: 15px 20px; }
.section-title { font-size: 1.8rem; }
.card { padding: 25px; }
.step { padding-left: 80px; }
.step::before { width: 50px; height: 50px; font-size: 1.5rem; }
.flow-diagram { flex-direction: column; }
}
</style>
</head>
<body>
<div class="progress-container">
<div class="progress-bar" id="progressBar"></div>
</div>
<div class="hero">
<div class="hero-content">
<div class="pipe-icon">⚡</div>
<h1>Master Piping to Node!</h1>
<div class="command-display">echo "data" | node script.js</div>
<p>Stream data into Node.js! 🌊</p>
</div>
</div>
<div class="container">
<!-- What Is It -->
<section class="section">
<h2 class="section-title">🤔 What Is This Command?</h2>
<div class="card">
<p style="font-size: 1.2rem; margin-bottom: 20px;">
This command <span class="highlight">pipes data from echo into a Node.js script</span> through stdin (standard input) - it's like sending a message through a tube directly into your program! ⚡
</p>
<p style="margin-bottom: 20px;">
Think of it like a water pipe! 🚰 The <code>echo</code> command produces output (water), the pipe <code>|</code> connects them, and your Node.js script receives it as input. Instead of typing data manually or reading from a file, you can stream data directly into your script!
</p>
<div class="info">
<strong>Breaking It Down:</strong>
<ul style="margin-left: 30px; margin-top: 10px; line-height: 2;">
<li><code class="code-echo">echo "data"</code> - Outputs text to stdout</li>
<li><code class="code-pipe">|</code> - Pipe operator (connects commands)</li>
<li><code>node script.js</code> - Runs Node.js script</li>
<li>Data flows: echo → pipe → Node stdin</li>
<li>Script reads from <code>process.stdin</code></li>
</ul>
</div>
<div style="margin-top: 30px;">
<h3 style="color: var(--accent-pink); margin-bottom: 15px;">What's stdin? 🔍</h3>
<p>stdin (standard input) is a stream where programs receive input data. By default it's your keyboard, but with pipes, it can be output from another command! It's one of three standard streams: stdin (input), stdout (output), and stderr (errors).</p>
</div>
</div>
</section>
<!-- Flow Diagram -->
<section class="section">
<h2 class="section-title">📊 How Data Flows</h2>
<div class="card">
<h3 style="margin-bottom: 20px; text-align: center;">The Pipe Pipeline! 🌊</h3>
<div class="flow-diagram">
<div class="flow-box">
<div style="font-size: 3rem; margin-bottom: 10px;">📢</div>
<h4 style="color: var(--accent-cyan);">echo "data"</h4>
<p style="color: var(--text-secondary); font-size: 0.9rem;">Produces output</p>
</div>
<div class="flow-arrow">→</div>
<div class="flow-box">
<div style="font-size: 3rem; margin-bottom: 10px;">🚰</div>
<h4 style="color: var(--accent-cyan);">| (pipe)</h4>
<p style="color: var(--text-secondary); font-size: 0.9rem;">Connects streams</p>
</div>
<div class="flow-arrow">→</div>
<div class="flow-box">
<div style="font-size: 3rem; margin-bottom: 10px;">📥</div>
<h4 style="color: var(--accent-cyan);">process.stdin</h4>
<p style="color: var(--text-secondary); font-size: 0.9rem;">Node receives</p>
</div>
</div>
<div class="success" style="margin-top: 30px;">
<strong>Result:</strong> Data flows seamlessly from one command to another!
</div>
</div>
</section>
<!-- Why Use It -->
<section class="section">
<h2 class="section-title">✨ Why Use Pipes?</h2>
<div class="card">
<div class="feature-grid">
<div class="feature-card">
<div class="feature-icon">🔗</div>
<div class="feature-title">Chain Commands</div>
<p style="color: var(--text-secondary);">Connect multiple tools!</p>
</div>
<div class="feature-card">
<div class="feature-icon">🚀</div>
<div class="feature-title">Efficient</div>
<p style="color: var(--text-secondary);">Stream processing!</p>
</div>
<div class="feature-card">
<div class="feature-icon">🎯</div>
<div class="feature-title">Flexible</div>
<p style="color: var(--text-secondary);">Any data source!</p>
</div>
<div class="feature-card">
<div class="feature-icon">💾</div>
<div class="feature-title">No Files Needed</div>
<p style="color: var(--text-secondary);">Direct streaming!</p>
</div>
<div class="feature-card">
<div class="feature-icon">🔄</div>
<div class="feature-title">Real-time</div>
<p style="color: var(--text-secondary);">Process as it comes!</p>
</div>
<div class="feature-card">
<div class="feature-icon">🛠️</div>
<div class="feature-title">Unix Philosophy</div>
<p style="color: var(--text-secondary);">Do one thing well!</p>
</div>
</div>
</div>
</section>
<!-- How It Works -->
<section class="section">
<h2 class="section-title">⚙️ How Does It Work?</h2>
<div class="card">
<div class="steps">
<div class="step">
<h3>Step 1: Echo Produces Output</h3>
<p>echo command outputs "data" to stdout (standard output).</p>
</div>
<div class="step">
<h3>Step 2: Pipe Connects Streams</h3>
<p>The | operator redirects echo's stdout to the next command's stdin.</p>
</div>
<div class="step">
<h3>Step 3: Node Starts</h3>
<p>Node.js launches and runs script.js.</p>
</div>
<div class="step">
<h3>Step 4: Script Reads stdin</h3>
<p>Script accesses data through process.stdin stream.</p>
</div>
<div class="step">
<h3>Step 5: Process Data</h3>
<p>Script processes the incoming data as it arrives.</p>
</div>
<div class="step">
<h3>Step 6: Output Results</h3>
<p>Script can output to stdout for further piping! 🎉</p>
</div>
</div>
</div>
</section>
<!-- Live Demo -->
<section class="section">
<h2 class="section-title">🎮 Interactive Demo</h2>
<div class="demo-container">
<div style="margin-bottom: 30px; text-align: center;">
<h4 style="margin-bottom: 15px;">See Piping in Action! ⚡</h4>
<button class="demo-button" onclick="simulatePipe()">
<span>🚰</span>
<span>Simple Pipe</span>
</button>
<button class="demo-button" onclick="simulateJSON()">
<span>📦</span>
<span>JSON Pipe</span>
</button>
<button class="demo-button" onclick="simulateChain()">
<span>🔗</span>
<span>Command Chain</span>
</button>
</div>
<div class="terminal" id="terminal">
<div class="terminal-line">
<span class="terminal-prompt">$</span>
<span style="color: var(--text-secondary);"> Ready to pipe data...</span>
</div>
</div>
</div>
</section>
<!-- Code Breakdown -->
<section class="section">
<h2 class="section-title">💻 Usage Examples</h2>
<div class="card">
<div class="tabs">
<button class="tab active" onclick="switchTab('basic')">Basic Example</button>
<button class="tab" onclick="switchTab('json')">JSON Data</button>
<button class="tab" onclick="switchTab('files')">File Processing</button>
<button class="tab" onclick="switchTab('advanced')">Advanced</button>
</div>
<div id="basic" class="tab-content active">
<h3 style="color: var(--accent-pink); margin-bottom: 15px;">Basic stdin Reading</h3>
<div class="code-block">
<div class="code-header">
<div class="terminal-dots">
<div class="terminal-dot dot-red"></div>
<div class="terminal-dot dot-yellow"></div>
<div class="terminal-dot dot-green"></div>
</div>
<button class="copy-btn" onclick="copyCode('basic-code')">📋 Copy</button>
</div>
<pre><code id="basic-code"><span class="code-comment">// script.js - Read from stdin</span>
process.stdin.on(<span class="code-string">'data'</span>, (data) => {
console.log(<span class="code-string">'Received:'</span>, data.toString());
});
<span class="code-comment">// Usage in terminal:</span>
echo <span class="code-string">"Hello World"</span> | node script.js
<span class="code-comment"># Output: Received: Hello World</span>
<span class="code-comment">// Alternative: read all data at once</span>
<span class="code-keyword">let</span> input = <span class="code-string">''</span>;
process.stdin.on(<span class="code-string">'data'</span>, chunk => input += chunk);
process.stdin.on(<span class="code-string">'end'</span>, () => {
console.log(<span class="code-string">'Complete input:'</span>, input);
});</code></pre>
</div>
<div class="success" style="margin-top: 15px;">
<strong>Result:</strong> Script receives and processes piped data!
</div>
</div>
<div id="json" class="tab-content">
<h3 style="color: var(--accent-pink); margin-bottom: 15px;">Processing JSON Data</h3>
<div class="code-block">
<div class="code-header">
<div class="terminal-dots">
<div class="terminal-dot dot-red"></div>
<div class="terminal-dot dot-yellow"></div>
<div class="terminal-dot dot-green"></div>
</div>
<button class="copy-btn" onclick="copyCode('json-code')">📋 Copy</button>
</div>
<pre><code id="json-code"><span class="code-comment">// process-json.js</span>
<span class="code-keyword">let</span> jsonData = <span class="code-string">''</span>;
process.stdin.on(<span class="code-string">'data'</span>, chunk => {
jsonData += chunk;
});
process.stdin.on(<span class="code-string">'end'</span>, () => {
<span class="code-keyword">try</span> {
<span class="code-keyword">const</span> data = JSON.parse(jsonData);
console.log(<span class="code-string">'Name:'</span>, data.name);
console.log(<span class="code-string">'Age:'</span>, data.age);
} <span class="code-keyword">catch</span> (err) {
console.error(<span class="code-string">'Invalid JSON'</span>, err);
}
});
<span class="code-comment">// Usage:</span>
echo <span class="code-string">'{"name":"Alice","age":30}'</span> | node process-json.js
<span class="code-comment"># Output:</span>
<span class="code-comment"># Name: Alice</span>
<span class="code-comment"># Age: 30</span></code></pre>
</div>
<div class="tip" style="margin-top: 15px;">
<strong>Pro Tip:</strong> Always handle JSON parsing errors when reading from stdin!
</div>
</div>
<div id="files" class="tab-content">
<h3 style="color: var(--accent-pink); margin-bottom: 15px;">File Processing</h3>
<div class="code-block">
<div class="code-header">
<div class="terminal-dots">
<div class="terminal-dot dot-red"></div>
<div class="terminal-dot dot-yellow"></div>
<div class="terminal-dot dot-green"></div>
</div>
<button class="copy-btn" onclick="copyCode('files-code')">📋 Copy</button>
</div>
<pre><code id="files-code"><span class="code-comment">// line-counter.js - Count lines from stdin</span>
<span class="code-keyword">let</span> lineCount = <span class="code-keyword">0</span>;
process.stdin.on(<span class="code-string">'data'</span>, (chunk) => {
lineCount += chunk.toString().split(<span class="code-string">'\n'</span>).length - <span class="code-keyword">1</span>;
});
process.stdin.on(<span class="code-string">'end'</span>, () => {
console.log(<span class="code-string">`Total lines: ${lineCount}`</span>);
});
<span class="code-comment">// Usage with files:</span>
cat file.txt | node line-counter.js
<span class="code-comment">// Usage with command output:</span>
ls -la | node line-counter.js
<span class="code-comment">// Chain multiple commands:</span>
cat data.txt | grep <span class="code-string">"error"</span> | node line-counter.js</code></pre>
</div>
</div>
<div id="advanced" class="tab-content">
<h3 style="color: var(--accent-pink); margin-bottom: 15px;">Advanced Patterns</h3>
<div class="code-block">
<div class="code-header">
<div class="terminal-dots">
<div class="terminal-dot dot-red"></div>
<div class="terminal-dot dot-yellow"></div>
<div class="terminal-dot dot-green"></div>
</div>
<button class="copy-btn" onclick="copyCode('advanced-code')">📋 Copy</button>
</div>
<pre><code id="advanced-code"><span class="code-comment">// transform.js - Transform and pipe to next command</span>
process.stdin
.on(<span class="code-string">'data'</span>, (chunk) => {
<span class="code-keyword">const</span> transformed = chunk
.toString()
.toUpperCase()
.trim();
process.stdout.write(transformed + <span class="code-string">'\n'</span>);
});
<span class="code-comment">// Chain transformations:</span>
echo <span class="code-string">"hello"</span> | node transform.js | node another-script.js
<span class="code-comment">// Using readline for line-by-line processing:</span>
<span class="code-keyword">const</span> readline = require(<span class="code-string">'readline'</span>);
<span class="code-keyword">const</span> rl = readline.createInterface({
input: process.stdin,
output: process.stdout,
terminal: <span class="code-keyword">false</span>
});
rl.on(<span class="code-string">'line'</span>, (line) => {
console.log(<span class="code-string">`Processing: ${line}`</span>);
});
<span class="code-comment">// With async/await (Node 16+):</span>
<span class="code-keyword">const</span> { stdin } = process;
<span class="code-keyword">for await</span> (<span class="code-keyword">const</span> chunk <span class="code-keyword">of</span> stdin) {
console.log(<span class="code-string">'Chunk:'</span>, chunk.toString());
}</code></pre>
</div>
</div>
</div>
</section>
<!-- Common Mistakes -->
<section class="section">
<h2 class="section-title">❌ Common Mistakes</h2>
<div class="card">
<div class="accordion">
<div class="accordion-item">
<div class="accordion-header" onclick="toggleAccordion(this)">
<span><strong>1. Not Handling 'end' Event</strong></span>
<span class="accordion-icon">▼</span>
</div>
<div class="accordion-content">
<div class="accordion-body">
<div class="warning">
<strong>Problem:</strong> Script exits before processing all data
</div>
<div class="success" style="margin-top: 15px;">
<strong>Solution:</strong> Always listen for 'end' event to know when input is complete!
</div>
</div>
</div>
</div>
<div class="accordion-item">
<div class="accordion-header" onclick="toggleAccordion(this)">
<span><strong>2. Forgetting toString()</strong></span>
<span class="accordion-icon">▼</span>
</div>
<div class="accordion-content">
<div class="accordion-body">
<div class="warning">
<strong>Problem:</strong> Data comes as Buffer, not string
</div>
<div class="success" style="margin-top: 15px;">
<strong>Solution:</strong> Use <code>chunk.toString()</code> to convert Buffer to string!
</div>
</div>
</div>
</div>
<div class="accordion-item">
<div class="accordion-header" onclick="toggleAccordion(this)">
<span><strong>3. Not Setting Encoding</strong></span>
<span class="accordion-icon">▼</span>
</div>
<div class="accordion-content">
<div class="accordion-body">
<div class="warning">
<strong>Problem:</strong> Character encoding issues with special characters
</div>
<div class="success" style="margin-top: 15px;">
<strong>Solution:</strong> Set encoding: <code>process.stdin.setEncoding('utf8')</code>!
</div>
</div>
</div>
</div>
<div class="accordion-item">
<div class="accordion-header" onclick="toggleAccordion(this)">
<span><strong>4. Blocking Operations</strong></span>
<span class="accordion-icon">▼</span>
</div>
<div class="accordion-content">
<div class="accordion-body">
<div class="warning">
<strong>Problem:</strong> Using synchronous operations blocks the stream
</div>
<div class="success" style="margin-top: 15px;">
<strong>Solution:</strong> Use async operations to keep stream flowing!
</div>
</div>
</div>
</div>
</div>
</div>
</section>
<!-- Pro Tips -->
<section class="section">
<h2 class="section-title">🚀 Pro Tips</h2>
<div class="card">
<div class="tip">
<strong>Set encoding early</strong> - Use <code>process.stdin.setEncoding('utf8')</code> to avoid Buffer conversion!
</div>
<div class="tip">
<strong>Use readline module</strong> - For line-by-line processing, readline is cleaner!
</div>
<div class="tip">
<strong>Handle errors</strong> - Always add error handlers to stdin stream!
</div>
<div class="tip">
<strong>Check for TTY</strong> - Use <code>process.stdin.isTTY</code> to detect if input is piped!
</div>
<div class="tip">
<strong>Async iteration</strong> - Node 16+ supports <code>for await...of</code> on stdin!
</div>
<div class="tip">
<strong>Backpressure</strong> - Handle <code>process.stdout.write()</code> return value for large data!
</div>
<div class="tip">
<strong>Testing</strong> - Test with <code>echo</code>, files, and command output!
</div>
</div>
</section>
<!-- Quiz -->
<section class="section">
<h2 class="section-title">🎯 Knowledge Check Quiz</h2>
<div class="quiz-container">
<p style="margin-bottom: 30px; font-size: 1.1rem;">Test your understanding! 🧠</p>
<div class="quiz-question">
<h3>Question 1: What does the | operator do?</h3>
<div class="quiz-options">
<div class="quiz-option" onclick="checkAnswer(this, false, 1)">A) Performs bitwise OR</div>
<div class="quiz-option" onclick="checkAnswer(this, true, 1)">B) Pipes stdout to stdin of next command</div>
<div class="quiz-option" onclick="checkAnswer(this, false, 1)">C) Separates commands</div>
</div>
<div class="quiz-feedback" id="feedback1"></div>
</div>
<div class="quiz-question">
<h3>Question 2: How do you read from stdin in Node.js?</h3>
<div class="quiz-options">
<div class="quiz-option" onclick="checkAnswer(this, false, 2)">A) console.read()</div>
<div class="quiz-option" onclick="checkAnswer(this, true, 2)">B) process.stdin.on('data', callback)</div>
<div class="quiz-option" onclick="checkAnswer(this, false, 2)">C) fs.readStdin()</div>
</div>
<div class="quiz-feedback" id="feedback2"></div>
</div>
<div class="quiz-question">
<h3>Question 3: What type is stdin data by default?</h3>
<div class="quiz-options">
<div class="quiz-option" onclick="checkAnswer(this, false, 3)">A) String</div>
<div class="quiz-option" onclick="checkAnswer(this, true, 3)">B) Buffer</div>
<div class="quiz-option" onclick="checkAnswer(this, false, 3)">C) Array</div>
</div>
<div class="quiz-feedback" id="feedback3"></div>
</div>
<div id="quizScore" style="margin-top: 30px; padding: 20px; background: var(--bg-secondary); border-radius: 12px; display: none;">
<h3 style="color: var(--accent-green); font-size: 1.5rem;">🎉 Quiz Complete!</h3>
<p id="scoreText" style="font-size: 1.2rem; margin-top: 10px;"></p>
</div>
</div>
</section>
<!-- Summary Card -->
<section class="section">
<h2 class="section-title">📚 Quick Reference</h2>
<div class="cheat-sheet">
<h3 style="margin-bottom: 20px; font-size: 2rem;">Piping Cheat Sheet! 🔖</h3>
<div class="cheat-grid">
<div class="cheat-item">
<h4>⚡ Basic Syntax</h4>
<p><code>echo "data" | node script.js</code></p>
<p style="font-size: 0.85rem; margin-top: 5px;">Pipe to Node</p>
</div>
<div class="cheat-item">
<h4>📥 Read Data</h4>
<p><code>process.stdin.on('data', fn)</code></p>
<p style="font-size: 0.85rem; margin-top: 5px;">Listen for input</p>
</div>
<div class="cheat-item">
<h4>🏁 End Event</h4>
<p><code>process.stdin.on('end', fn)</code></p>
<p style="font-size: 0.85rem; margin-top: 5px;">Input complete</p>
</div>
<div class="cheat-item">
<h4>🔤 Set Encoding</h4>
<p><code>stdin.setEncoding('utf8')</code></p>
<p style="font-size: 0.85rem; margin-top: 5px;">Auto-convert</p>
</div>
<div class="cheat-item">
<h4>📝 Line-by-Line</h4>
<p><code>readline.createInterface</code></p>
<p style="font-size: 0.85rem; margin-top: 5px;">Process lines</p>
</div>
<div class="cheat-item">
<h4>🔗 Chain Commands</h4>
<p><code>cmd1 | node | cmd2</code></p>
<p style="font-size: 0.85rem; margin-top: 5px;">Multiple pipes</p>
</div>
<div class="cheat-item">
<h4>📄 From Files</h4>
<p><code>cat file.txt | node script.js</code></p>
<p style="font-size: 0.85rem; margin-top: 5px;">File input</p>
</div>
<div class="cheat-item">
<h4>✅ Check TTY</h4>
<p><code>process.stdin.isTTY</code></p>
<p style="font-size: 0.85rem; margin-top: 5px;">Detect piping</p>
</div>
</div>
</div>
</section>
<!-- Footer -->
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<p style="font-size: 1.2rem; margin-bottom: 20px;">You now understand <strong>piping to Node.js</strong>! 🚀</p>
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<p style="color: var(--text-secondary); font-size: 0.9rem;">Made with ❤️ for developers learning Node.js</p>
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