Complete the async function:
📦 Node.js-> Command Line
✨ The Prompt Phrase
async function fetchData() {
return awaitPromise .resolve('Hello!');
}
💻 Code Preview
📦 All-in-One Code
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</head>
<body>
<div class="progress-container">
<div class="progress-bar" id="progressBar"></div>
</div>
<div class="hero">
<div class="hero-content">
<h1>⏳ Master Async/Await in JavaScript!</h1>
<div class="command-display">async function fetchData() {<br> return await Promise.resolve('Hello!');<br>}</div>
<p>Write asynchronous code that looks synchronous! 🚀</p>
</div>
</div>
<div class="container">
<!-- What Is It Section -->
<section class="section" id="what-is-it">
<h2 class="section-title">🤔 What Is It?</h2>
<div class="card">
<p style="font-size: 1.2rem; margin-bottom: 20px;">
<span class="highlight">Async/await</span> is a modern way to handle asynchronous operations in JavaScript - making your code cleaner and easier to read! ✨
</p>
<p style="margin-bottom: 20px;">
Think of it like ordering food at a restaurant: Instead of standing at the counter waiting (blocking), you sit down, order, and the waiter brings your food when it's ready (non-blocking). Meanwhile, you can chat with friends! 🍕
</p>
<div class="info">
<strong>In Simple Terms:</strong> <code>async/await</code> lets you write code that waits for things (like API calls or file reads) without freezing your entire program. It's like having a personal assistant who handles the waiting for you! 🎯
</div>
<div style="margin-top: 30px;">
<h3 style="color: var(--accent-pink); margin-bottom: 15px;">Breaking It Down 🔍</h3>
<ul style="margin-left: 30px; line-height: 2;">
<li><strong>async</strong>: Declares a function that returns a Promise</li>
<li><strong>await</strong>: Pauses execution until the Promise resolves</li>
<li><strong>Promise</strong>: Represents a value that will be available in the future</li>
</ul>
</div>
</div>
</section>
<!-- Why Use It Section -->
<section class="section" id="why-use-it">
<h2 class="section-title">✨ Why Use Async/Await?</h2>
<div class="card">
<div class="cheat-grid">
<div class="cheat-item">
<h4>📖 Readable Code</h4>
<p>Looks like regular synchronous code - much easier to understand!</p>
</div>
<div class="cheat-item">
<h4>🎯 Error Handling</h4>
<p>Use try/catch blocks just like synchronous code!</p>
</div>
<div class="cheat-item">
<h4>🔗 No Callback Hell</h4>
<p>Avoid nested callbacks and "pyramid of doom"!</p>
</div>
<div class="cheat-item">
<h4>🐛 Easy Debugging</h4>
<p>Stack traces are clearer and easier to follow!</p>
</div>
<div class="cheat-item">
<h4>🎨 Modern Standard</h4>
<p>The preferred way to handle async operations in modern JavaScript!</p>
</div>
<div class="cheat-item">
<h4>⚡ Better Performance</h4>
<p>Can easily run multiple async operations in parallel!</p>
</div>
</div>
</div>
</section>
<!-- How Does It Work Section -->
<section class="section" id="how-it-works">
<h2 class="section-title">⚙️ How Does It Work?</h2>
<div class="card">
<p style="margin-bottom: 30px;">Let's break down the code step by step! 🔬</p>
<div class="steps">
<div class="step">
<h3>Step 1: The async Keyword</h3>
<div class="code-block">
<pre><code><span class="code-keyword">async function</span> <span class="code-function">fetchData</span>() {</code></pre>
</div>
<p>The <code>async</code> keyword before <code>function</code> tells JavaScript: "This function will handle asynchronous operations." It automatically wraps the return value in a Promise! 🎁</p>
</div>
<div class="step">
<h3>Step 2: The await Keyword</h3>
<div class="code-block">
<pre><code> <span class="code-keyword">return await</span> Promise.<span class="code-function">resolve</span>(<span class="code-string">'Hello!'</span>);</code></pre>
</div>
<p><code>await</code> pauses the function execution until the Promise resolves. It's like saying "Wait for this to finish before moving on!" ⏸️</p>
</div>
<div class="step">
<h3>Step 3: Promise.resolve()</h3>
<div class="code-block">
<pre><code>Promise.<span class="code-function">resolve</span>(<span class="code-string">'Hello!'</span>)</code></pre>
</div>
<p>Creates a Promise that immediately resolves with the value 'Hello!'. In real code, this could be an API call, database query, or file read! 📡</p>
</div>
<div class="step">
<h3>Step 4: Return the Result</h3>
<div class="code-block">
<pre><code><span class="code-keyword">return</span> <span class="code-keyword">await</span> ...</code></pre>
</div>
<p>Returns the resolved value ('Hello!') to whoever calls this function. The function itself returns a Promise! 🎯</p>
</div>
</div>
<div class="success" style="margin-top: 30px;">
<strong>Key Point:</strong> An <code>async</code> function ALWAYS returns a Promise, even if you return a regular value!
</div>
</div>
</section>
<!-- Timeline Visualization -->
<section class="section" id="timeline">
<h2 class="section-title">⏱️ Execution Timeline</h2>
<div class="card">
<p style="margin-bottom: 20px;">Here's what happens when you call the function:</p>
<div class="timeline">
<div class="timeline-item">
<div class="timeline-dot"></div>
<div class="timeline-content">
<strong>1. Function Called</strong>
<p>fetchData() is invoked</p>
</div>
</div>
<div class="timeline-item">
<div class="timeline-dot"></div>
<div class="timeline-content">
<strong>2. Await Encountered</strong>
<p>Function pauses at 'await', waiting for Promise</p>
</div>
</div>
<div class="timeline-item">
<div class="timeline-dot"></div>
<div class="timeline-content">
<strong>3. Promise Resolves</strong>
<p>Promise.resolve('Hello!') completes immediately</p>
</div>
</div>
<div class="timeline-item">
<div class="timeline-dot"></div>
<div class="timeline-content">
<strong>4. Function Resumes</strong>
<p>Returns 'Hello!' wrapped in a Promise</p>
</div>
</div>
</div>
</div>
</section>
<!-- Interactive Demo -->
<section class="section" id="demo">
<h2 class="section-title">🎮 Interactive Demo</h2>
<div class="demo-container">
<h3 style="margin-bottom: 20px;">Try It Yourself! 🎯</h3>
<p style="margin-bottom: 30px;">Click the buttons to see async/await in action!</p>
<div style="display: flex; gap: 10px; flex-wrap: wrap; margin-bottom: 20px;">
<button class="demo-button" onclick="runAsyncDemo()">
<span>▶️</span>
<span>Run Async Function</span>
</button>
<button class="demo-button" onclick="runSlowDemo()">
<span>⏱️</span>
<span>Simulate Slow Operation</span>
</button>
<button class="demo-button" onclick="runParallelDemo()">
<span>⚡</span>
<span>Run in Parallel</span>
</button>
</div>
<div class="demo-output" id="demoOutput">
<div style="color: var(--text-secondary);">Click a button to see the output...</div>
</div>
</div>
</section>
<!-- Code Examples -->
<section class="section" id="examples">
<h2 class="section-title">💻 Real-World Examples</h2>
<div class="card">
<div class="tabs">
<button class="tab active" onclick="switchTab('basic')">Basic Example</button>
<button class="tab" onclick="switchTab('api')">API Call</button>
<button class="tab" onclick="switchTab('error')">Error Handling</button>
<button class="tab" onclick="switchTab('parallel')">Parallel Execution</button>
</div>
<div id="basic" class="tab-content active">
<h3 style="color: var(--accent-pink); margin-bottom: 15px;">Basic Async/Await</h3>
<div class="code-block">
<div class="code-header">
<span class="code-lang">JavaScript</span>
<button class="copy-btn" onclick="copyCode(this, 'basic-code')">📋 Copy</button>
</div>
<pre><code id="basic-code"><span class="code-comment">// Define an async function</span>
<span class="code-keyword">async function</span> <span class="code-function">fetchData</span>() {
<span class="code-keyword">return await</span> Promise.<span class="code-function">resolve</span>(<span class="code-string">'Hello!'</span>);
}
<span class="code-comment">// Call the async function</span>
<span class="code-function">fetchData</span>().<span class="code-function">then</span>(<span class="code-variable">result</span> => {
console.<span class="code-function">log</span>(<span class="code-variable">result</span>); <span class="code-comment">// Output: Hello!</span>
});
<span class="code-comment">// Or use await in another async function</span>
<span class="code-keyword">async function</span> <span class="code-function">main</span>() {
<span class="code-keyword">const</span> <span class="code-variable">data</span> = <span class="code-keyword">await</span> <span class="code-function">fetchData</span>();
console.<span class="code-function">log</span>(<span class="code-variable">data</span>); <span class="code-comment">// Output: Hello!</span>
}
<span class="code-function">main</span>();</code></pre>
</div>
</div>
<div id="api" class="tab-content">
<h3 style="color: var(--accent-pink); margin-bottom: 15px;">Fetching Data from API</h3>
<div class="code-block">
<div class="code-header">
<span class="code-lang">JavaScript</span>
<button class="copy-btn" onclick="copyCode(this, 'api-code')">📋 Copy</button>
</div>
<pre><code id="api-code"><span class="code-comment">// Fetch data from an API</span>
<span class="code-keyword">async function</span> <span class="code-function">getUserData</span>(<span class="code-variable">userId</span>) {
<span class="code-comment">// Wait for the fetch to complete</span>
<span class="code-keyword">const</span> <span class="code-variable">response</span> = <span class="code-keyword">await</span> <span class="code-function">fetch</span>(<span class="code-string">`https://api.example.com/users/${userId}`</span>);
<span class="code-comment">// Wait for JSON parsing</span>
<span class="code-keyword">const</span> <span class="code-variable">data</span> = <span class="code-keyword">await</span> <span class="code-variable">response</span>.<span class="code-function">json</span>();
<span class="code-keyword">return</span> <span class="code-variable">data</span>;
}
<span class="code-comment">// Usage</span>
<span class="code-keyword">async function</span> <span class="code-function">displayUser</span>() {
<span class="code-keyword">const</span> <span class="code-variable">user</span> = <span class="code-keyword">await</span> <span class="code-function">getUserData</span>(<span class="code-number">123</span>);
console.<span class="code-function">log</span>(<span class="code-variable">user</span>.<span class="code-variable">name</span>);
}</code></pre>
</div>
</div>
<div id="error" class="tab-content">
<h3 style="color: var(--accent-pink); margin-bottom: 15px;">Error Handling with Try/Catch</h3>
<div class="code-block">
<div class="code-header">
<span class="code-lang">JavaScript</span>
<button class="copy-btn" onclick="copyCode(this, 'error-code')">📋 Copy</button>
</div>
<pre><code id="error-code"><span class="code-keyword">async function</span> <span class="code-function">fetchDataSafely</span>() {
<span class="code-keyword">try</span> {
<span class="code-comment">// Try to fetch data</span>
<span class="code-keyword">const</span> <span class="code-variable">response</span> = <span class="code-keyword">await</span> <span class="code-function">fetch</span>(<span class="code-string">'https://api.example.com/data'</span>);
<span class="code-keyword">if</span> (!<span class="code-variable">response</span>.<span class="code-variable">ok</span>) {
<span class="code-keyword">throw new</span> <span class="code-function">Error</span>(<span class="code-string">'Network response was not ok'</span>);
}
<span class="code-keyword">const</span> <span class="code-variable">data</span> = <span class="code-keyword">await</span> <span class="code-variable">response</span>.<span class="code-function">json</span>();
<span class="code-keyword">return</span> <span class="code-variable">data</span>;
} <span class="code-keyword">catch</span> (<span class="code-variable">error</span>) {
<span class="code-comment">// Handle any errors</span>
console.<span class="code-function">error</span>(<span class="code-string">'Error fetching data:'</span>, <span class="code-variable">error</span>);
<span class="code-keyword">return</span> <span class="code-keyword">null</span>;
}
}
<span class="code-comment">// Usage</span>
<span class="code-keyword">const</span> <span class="code-variable">data</span> = <span class="code-keyword">await</span> <span class="code-function">fetchDataSafely</span>();</code></pre>
</div>
</div>
<div id="parallel" class="tab-content">
<h3 style="color: var(--accent-pink); margin-bottom: 15px;">Running Operations in Parallel</h3>
<div class="code-block">
<div class="code-header">
<span class="code-lang">JavaScript</span>
<button class="copy-btn" onclick="copyCode(this, 'parallel-code')">📋 Copy</button>
</div>
<pre><code id="parallel-code"><span class="code-comment">// ❌ Sequential (slow) - waits for each one</span>
<span class="code-keyword">async function</span> <span class="code-function">sequential</span>() {
<span class="code-keyword">const</span> <span class="code-variable">user</span> = <span class="code-keyword">await</span> <span class="code-function">fetchUser</span>(); <span class="code-comment">// Wait 1 second</span>
<span class="code-keyword">const</span> <span class="code-variable">posts</span> = <span class="code-keyword">await</span> <span class="code-function">fetchPosts</span>(); <span class="code-comment">// Wait another 1 second</span>
<span class="code-keyword">return</span> { <span class="code-variable">user</span>, <span class="code-variable">posts</span> }; <span class="code-comment">// Total: 2 seconds</span>
}
<span class="code-comment">// ✅ Parallel (fast) - runs simultaneously</span>
<span class="code-keyword">async function</span> <span class="code-function">parallel</span>() {
<span class="code-comment">// Start both operations at once</span>
<span class="code-keyword">const</span> [<span class="code-variable">user</span>, <span class="code-variable">posts</span>] = <span class="code-keyword">await</span> Promise.<span class="code-function">all</span>([
<span class="code-function">fetchUser</span>(),
<span class="code-function">fetchPosts</span>()
]);
<span class="code-keyword">return</span> { <span class="code-variable">user</span>, <span class="code-variable">posts</span> }; <span class="code-comment">// Total: 1 second!</span>
}
<span class="code-comment">// Even better: with error handling</span>
<span class="code-keyword">async function</span> <span class="code-function">parallelSafe</span>() {
<span class="code-keyword">const</span> <span class="code-variable">results</span> = <span class="code-keyword">await</span> Promise.<span class="code-function">allSettled</span>([
<span class="code-function">fetchUser</span>(),
<span class="code-function">fetchPosts</span>()
]);
<span class="code-keyword">return</span> <span class="code-variable">results</span>;
}</code></pre>
</div>
</div>
</div>
</section>
<!-- Common Mistakes Section -->
<section class="section" id="mistakes">
<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. Forgetting the 'async' Keyword</strong></span>
<span class="accordion-icon">▼</span>
</div>
<div class="accordion-content">
<div class="accordion-body">
<div class="warning">
<strong>Error:</strong> You can't use 'await' in a non-async function!
</div>
<div class="code-block" style="margin-top: 15px;">
<pre><code><span class="code-comment">// ❌ Wrong - missing 'async'</span>
<span class="code-keyword">function</span> <span class="code-function">fetchData</span>() {
<span class="code-keyword">return await</span> Promise.<span class="code-function">resolve</span>(<span class="code-string">'Hello!'</span>); <span class="code-comment">// SyntaxError!</span>
}
<span class="code-comment">// ✅ Correct - has 'async'</span>
<span class="code-keyword">async function</span> <span class="code-function">fetchData</span>() {
<span class="code-keyword">return await</span> Promise.<span class="code-function">resolve</span>(<span class="code-string">'Hello!'</span>); <span class="code-comment">// Works!</span>
}</code></pre>
</div>
</div>
</div>
</div>
<div class="accordion-item">
<div class="accordion-header" onclick="toggleAccordion(this)">
<span><strong>2. Syntax Error: "awaitPromise" (Missing Space!)</strong></span>
<span class="accordion-icon">▼</span>
</div>
<div class="accordion-content">
<div class="accordion-body">
<div class="warning">
<strong>Common Typo:</strong> Writing "awaitPromise" instead of "await Promise"
</div>
<div class="code-block" style="margin-top: 15px;">
<pre><code><span class="code-comment">// ❌ Wrong - no space between await and Promise</span>
<span class="code-keyword">async function</span> <span class="code-function">fetchData</span>() {
<span class="code-keyword">return</span> awaitPromise.<span class="code-function">resolve</span>(<span class="code-string">'Hello!'</span>); <span class="code-comment">// ReferenceError!</span>
}
<span class="code-comment">// ✅ Correct - space between await and Promise</span>
<span class="code-keyword">async function</span> <span class="code-function">fetchData</span>() {
<span class="code-keyword">return await</span> Promise.<span class="code-function">resolve</span>(<span class="code-string">'Hello!'</span>); <span class="code-comment">// Works!</span>
}</code></pre>
</div>
<p style="margin-top: 15px;"><strong>Remember:</strong> <code>await</code> is a keyword, and <code>Promise</code> is an object. They need a space between them!</p>
</div>
</div>
</div>
<div class="accordion-item">
<div class="accordion-header" onclick="toggleAccordion(this)">
<span><strong>3. Not Handling Errors</strong></span>
<span class="accordion-icon">▼</span>
</div>
<div class="accordion-content">
<div class="accordion-body">
<div class="warning">
<strong>Problem:</strong> Unhandled promise rejections crash your app!
</div>
<div class="code-block" style="margin-top: 15px;">
<pre><code><span class="code-comment">// ❌ No error handling</span>
<span class="code-keyword">async function</span> <span class="code-function">fetchData</span>() {
<span class="code-keyword">const</span> <span class="code-variable">data</span> = <span class="code-keyword">await</span> <span class="code-function">fetch</span>(<span class="code-string">'/api/data'</span>); <span class="code-comment">// What if this fails?</span>
<span class="code-keyword">return</span> <span class="code-variable">data</span>;
}
<span class="code-comment">// ✅ With error handling</span>
<span class="code-keyword">async function</span> <span class="code-function">fetchData</span>() {
<span class="code-keyword">try</span> {
<span class="code-keyword">const</span> <span class="code-variable">data</span> = <span class="code-keyword">await</span> <span class="code-function">fetch</span>(<span class="code-string">'/api/data'</span>);
<span class="code-keyword">return</span> <span class="code-variable">data</span>;
} <span class="code-keyword">catch</span> (<span class="code-variable">error</span>) {
console.<span class="code-function">error</span>(<span class="code-string">'Failed to fetch:'</span>, <span class="code-variable">error</span>);
<span class="code-keyword">return</span> <span class="code-keyword">null</span>;
}
}</code></pre>
</div>
</div>
</div>
</div>
<div class="accordion-item">
<div class="accordion-header" onclick="toggleAccordion(this)">
<span><strong>4. Unnecessary 'await' on Return</strong></span>
<span class="accordion-icon">▼</span>
</div>
<div class="accordion-content">
<div class="accordion-body">
<div class="tip">
<strong>Optimization:</strong> You don't always need 'await' when returning!
</div>
<div class="code-block" style="margin-top: 15px;">
<pre><code><span class="code-comment">// Both work, but second is slightly better</span>
<span class="code-keyword">async function</span> <span class="code-function">fetchData1</span>() {
<span class="code-keyword">return await</span> Promise.<span class="code-function">resolve</span>(<span class="code-string">'Hello!'</span>);
}
<span class="code-comment">// Simpler - no need for await here</span>
<span class="code-keyword">async function</span> <span class="code-function">fetchData2</span>() {
<span class="code-keyword">return</span> Promise.<span class="code-function">resolve</span>(<span class="code-string">'Hello!'</span>);
}
<span class="code-comment">// BUT: Use await if you need try/catch</span>
<span class="code-keyword">async function</span> <span class="code-function">fetchData3</span>() {
<span class="code-keyword">try</span> {
<span class="code-keyword">return await</span> Promise.<span class="code-function">resolve</span>(<span class="code-string">'Hello!'</span>);
} <span class="code-keyword">catch</span> (<span class="code-variable">error</span>) {
console.<span class="code-function">error</span>(<span class="code-variable">error</span>);
}
}</code></pre>
</div>
</div>
</div>
</div>
<div class="accordion-item">
<div class="accordion-header" onclick="toggleAccordion(this)">
<span><strong>5. Sequential Instead of Parallel</strong></span>
<span class="accordion-icon">▼</span>
</div>
<div class="accordion-content">
<div class="accordion-body">
<div class="warning">
<strong>Performance Issue:</strong> Running independent operations sequentially wastes time!
</div>
<div class="code-block" style="margin-top: 15px;">
<pre><code><span class="code-comment">// ❌ Slow - waits for each one (3 seconds total)</span>
<span class="code-keyword">async function</span> <span class="code-function">slow</span>() {
<span class="code-keyword">const</span> <span class="code-variable">a</span> = <span class="code-keyword">await</span> <span class="code-function">fetchA</span>(); <span class="code-comment">// 1 second</span>
<span class="code-keyword">const</span> <span class="code-variable">b</span> = <span class="code-keyword">await</span> <span class="code-function">fetchB</span>(); <span class="code-comment">// 1 second</span>
<span class="code-keyword">const</span> <span class="code-variable">c</span> = <span class="code-keyword">await</span> <span class="code-function">fetchC</span>(); <span class="code-comment">// 1 second</span>
<span class="code-keyword">return</span> [<span class="code-variable">a</span>, <span class="code-variable">b</span>, <span class="code-variable">c</span>];
}
<span class="code-comment">// ✅ Fast - runs in parallel (1 second total)</span>
<span class="code-keyword">async function</span> <span class="code-function">fast</span>() {
<span class="code-keyword">const</span> [<span class="code-variable">a</span>, <span class="code-variable">b</span>, <span class="code-variable">c</span>] = <span class="code-keyword">await</span> Promise.<span class="code-function">all</span>([
<span class="code-function">fetchA</span>(),
<span class="code-function">fetchB</span>(),
<span class="code-function">fetchC</span>()
]);
<span class="code-keyword">return</span> [<span class="code-variable">a</span>, <span class="code-variable">b</span>, <span class="code-variable">c</span>];
}</code></pre>
</div>
</div>
</div>
</div>
</div>
</div>
</section>
<!-- Pro Tips Section -->
<section class="section" id="pro-tips">
<h2 class="section-title">🚀 Pro Tips</h2>
<div class="card">
<div class="cheat-grid">
<div class="cheat-item">
<h4>⚡ Promise.all()</h4>
<p>Run multiple async operations in parallel for better performance!</p>
</div>
<div class="cheat-item">
<h4>🛡️ Promise.allSettled()</h4>
<p>Like Promise.all() but doesn't fail if one promise rejects!</p>
</div>
<div class="cheat-item">
<h4>🏃 Promise.race()</h4>
<p>Returns the first promise that resolves or rejects!</p>
</div>
<div class="cheat-item">
<h4>🔄 Top-Level Await</h4>
<p>In ES modules, you can use await at the top level!</p>
</div>
<div class="cheat-item">
<h4>🎯 Arrow Functions</h4>
<p><code>const func = async () => {...}</code> works great!</p>
</div>
<div class="cheat-item">
<h4>📝 Debugging</h4>
<p>Use <code>console.log()</code> before await to track execution!</p>
</div>
</div>
<div class="success" style="margin-top: 30px;">
<strong>🎓 Best Practice:</strong> Always use try/catch for error handling in async functions, especially when dealing with external APIs or file operations!
</div>
</div>
</section>
<!-- Quiz Section -->
<section class="section" id="quiz">
<h2 class="section-title">🎯 Knowledge Check Quiz</h2>
<div class="quiz-container">
<p style="margin-bottom: 30px;">Test your understanding! Click on the correct answer. 🧠</p>
<div class="quiz-question">
<h3>Question 1: What does the 'async' keyword do?</h3>
<div class="quiz-options">
<div class="quiz-option" onclick="checkAnswer(this, false, 1)">
A) Makes the function run faster
</div>
<div class="quiz-option" onclick="checkAnswer(this, true, 1)">
B) Makes the function return a Promise
</div>
<div class="quiz-option" onclick="checkAnswer(this, false, 1)">
C) Pauses the function execution
</div>
<div class="quiz-option" onclick="checkAnswer(this, false, 1)">
D) Handles errors automatically
</div>
</div>
<div class="quiz-feedback" id="feedback1"></div>
</div>
<div class="quiz-question">
<h3>Question 2: What's wrong with "awaitPromise.resolve()"?</h3>
<div class="quiz-options">
<div class="quiz-option" onclick="checkAnswer(this, false, 2)">
A) Nothing, it's correct
</div>
<div class="quiz-option" onclick="checkAnswer(this, true, 2)">
B) Missing space between 'await' and 'Promise'
</div>
<div class="quiz-option" onclick="checkAnswer(this, false, 2)">
C) Should use 'async' instead
</div>
<div class="quiz-option" onclick="checkAnswer(this, false, 2)">
D) Promise.resolve() doesn't exist
</div>
</div>
<div class="quiz-feedback" id="feedback2"></div>
</div>
<div class="quiz-question">
<h3>Question 3: How do you run multiple async operations in parallel?</h3>
<div class="quiz-options">
<div class="quiz-option" onclick="checkAnswer(this, false, 3)">
A) Use multiple await statements
</div>
<div class="quiz-option" onclick="checkAnswer(this, true, 3)">
B) Use Promise.all() with await
</div>
<div class="quiz-option" onclick="checkAnswer(this, false, 3)">
C) Use async twice
</div>
<div class="quiz-option" onclick="checkAnswer(this, false, 3)">
D) You can't run them in parallel
</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);">🎉 Quiz Complete!</h3>
<p id="scoreText" style="font-size: 1.2rem; margin-top: 10px;"></p>
</div>
</div>
</section>
<!-- Cheat Sheet Section -->
<section class="section" id="cheat-sheet">
<h2 class="section-title">📚 Quick Reference Cheat Sheet</h2>
<div class="cheat-sheet">
<h3 style="margin-bottom: 20px; color: #1a202c;">Save this for later! 🔖</h3>
<div class="cheat-grid">
<div class="cheat-item">
<h4>🔑 async Keyword</h4>
<p><code>async function name() {}</code></p>
<p style="font-size: 0.85rem; margin-top: 5px;">Makes function return Promise</p>
</div>
<div class="cheat-item">
<h4>⏸️ await Keyword</h4>
<p><code>await promise</code></p>
<p style="font-size: 0.85rem; margin-top: 5px;">Pauses until Promise resolves</p>
</div>
<div class="cheat-item">
<h4>🛡️ Error Handling</h4>
<p><code>try { await... } catch(e) {}</code></p>
<p style="font-size: 0.85rem; margin-top: 5px;">Handle async errors</p>
</div>
<div class="cheat-item">
<h4>⚡ Parallel</h4>
<p><code>await Promise.all([...])</code></p>
<p style="font-size: 0.85rem; margin-top: 5px;">Run multiple at once</p>
</div>
<div class="cheat-item">
<h4>🏁 Race</h4>
<p><code>await Promise.race([...])</code></p>
<p style="font-size: 0.85rem; margin-top: 5px;">First to finish wins</p>
</div>
<div class="cheat-item">
<h4>✅ All Settled</h4>
<p><code>await Promise.allSettled([...])</code></p>
<p style="font-size: 0.85rem; margin-top: 5px;">Wait for all, no fail</p>
</div>
</div>
<div style="margin-top: 30px; padding: 20px; background: rgba(255,255,255,0.2); border-radius: 12px;">
<h4 style="color: #1a202c; margin-bottom: 15px;">🎯 Complete Template</h4>
<div class="code-block">
<pre><code><span class="code-comment">// Basic async/await pattern</span>
<span class="code-keyword">async function</span> <span class="code-function">fetchData</span>() {
<span class="code-keyword">try</span> {
<span class="code-keyword">const</span> <span class="code-variable">response</span> = <span class="code-keyword">await</span> <span class="code-function">fetch</span>(<span class="code-string">'/api/data'</span>);
<span class="code-keyword">const</span> <span class="code-variable">data</span> = <span class="code-keyword">await</span> <span class="code-variable">response</span>.<span class="code
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