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HTML CSS JavaScript Editor

Free online HTML, CSS, and JavaScript editor with live preview, interactive console, and responsive testing. Perfect for web development, frontend prototyping, and learning to code.

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Features

Live Preview

Instantly see the results of your HTML, CSS, and JavaScript as you type

Three-Panel Editing

Dedicated panels for HTML, CSS, and JavaScript code with synchronized editing

Interactive Console

View console.log outputs and debug JavaScript errors in real-time

Code Formatting

One-click formatting for beautiful, readable code with proper indentation

Syntax Highlighting

Enhanced readability with color-coded syntax for all three languages

Frequently Asked Questions

How do I create a responsive website layout using HTML CSS flexbox grid?

Learn how to create responsive layouts:

<!-- Responsive viewport meta tag -->
<meta name="viewport" content="width=device-width, initial-scale=1.0">

<!-- Flexbox container example -->
<div class="flex-container">
    <div class="flex-item">Item 1</div>
    <div class="flex-item">Item 2</div>
</div>

/* Flexbox layout */
.flex-container {
    display: flex;
    justify-content: space-between;
    flex-wrap: wrap;
}

/* Grid layout */
.grid-container {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 1rem;
}

/* Responsive breakpoints */
@media (max-width: 768px) {
    .flex-container {
        flex-direction: column;
    }
}

Test responsiveness by resizing the preview window in our editor.

What's the best way to learn frontend development for beginners?

Start with these fundamental examples:

<!DOCTYPE html>
<html>
<head>
    <title>My First Website</title>
    <link rel="stylesheet" href="styles.css">
</head>
<body>
    <header>
        <h1>Welcome to My Site</h1>
        <nav>
            <a href="#">Home</a>
            <a href="#">About</a>
        </nav>
    </header>
    <main>
        <p>Start with basic HTML structure</p>
    </main>
</body>
</html>

/* Basic styling */
body {
    font-family: Arial, sans-serif;
    line-height: 1.6;
    margin: 0;
    padding: 20px;
}

nav a {
    margin-right: 10px;
    text-decoration: none;
}

// Add interactivity
document.querySelector('h1').addEventListener('click', function() {
    this.style.color = '#' + Math.floor(Math.random()*16777215).toString(16);
});

Practice by modifying these examples and watching real-time changes. Try building simple projects like a personal website, a to-do list, or an interactive form.

How can I add Bootstrap or Material UI to my front-end project?

Here's how to integrate popular frameworks:

<!DOCTYPE html>
<html>
<head>
    <!-- Bootstrap CSS -->
    <link href="https://cdn.jsdelivr.net/npm/bootstrap@5.3.0/dist/css/bootstrap.min.css" rel="stylesheet">
    
    <!-- Material Icons -->
    <link href="https://fonts.googleapis.com/icon?family=Material+Icons" rel="stylesheet">
</head>
<body>
    <!-- Bootstrap example -->
    <div class="container">
        <button class="btn btn-primary">Click me</button>
    </div>

    <!-- Material icon example -->
    <span class="material-icons">favorite</span>

    <!-- Bootstrap JavaScript Bundle with Popper -->
    <script src="https://cdn.jsdelivr.net/npm/bootstrap@5.3.0/dist/js/bootstrap.bundle.min.js"></script>
</body>
</html>

After adding these CDN links, you can use the framework's classes and components in your HTML.

How do I troubleshoot JavaScript errors in my web development code?

Here are some debugging techniques:

// Basic console logging
console.log('Debugging started');

// Check variable values
const user = { name: 'John', age: 30 };
console.log('User:', user);

// Async code debugging
async function fetchData() {
    try {
        const response = await fetch('https://api.example.com/data');
        const data = await response.json();
        console.log('Data:', data);
    } catch (error) {
        console.error('Error:', error);
    }
}

// DOM debugging
const element = document.querySelector('#myElement');
console.log('Element:', element);

Use our built-in console panel to view these logs and error messages.

Can I build a dynamic website without a backend using only HTML CSS JavaScript?

Yes! Here's an example of a client-side todo app:

// Local storage example
const todos = JSON.parse(localStorage.getItem('todos')) || [];

function addTodo(text) {
    const todo = {
        id: Date.now(),
        text,
        completed: false
    };
    todos.push(todo);
    localStorage.setItem('todos', JSON.stringify(todos));
}

// API fetch example
async function getWeather(city) {
    const response = await fetch(
        `https://api.weatherapi.com/v1/current.json?q=${city}`
    );
    const data = await response.json();
    return data;
}

// DOM manipulation
function renderTodos() {
    const list = document.querySelector('#todoList');
    list.innerHTML = todos
        .map(todo => `
            <li class="${todo.completed ? 'completed' : ''}">
                ${todo.text}
            </li>
        `)
        .join('');
}

Our editor is perfect for learning these front-end development techniques.

How do I create animations and transitions with CSS and JavaScript?

Create engaging animations with CSS and JavaScript:

/* CSS Animations */
@keyframes slide {
    from { transform: translateX(0); }
    to { transform: translateX(100px); }
}

.animated-element {
    animation: slide 2s ease infinite;
}

/* CSS Transitions */
.button {
    transition: all 0.3s ease;
}

.button:hover {
    transform: scale(1.1);
    background-color: #ff0000;
}

// JavaScript animations
const element = document.querySelector('.element');

// Using Web Animations API
element.animate([
    { transform: 'translateY(0px)' },
    { transform: 'translateY(-20px)' }
], {
    duration: 1000,
    iterations: Infinity,
    direction: 'alternate'
});

// Class-based animation
element.addEventListener('click', () => {
    element.classList.add('animated');
});

Try these examples in our editor and watch the animations in real-time.

Where can I learn more about web development?

Explore these official resources and learning materials:

Official Specifications & Standards:

Learning Resources:

Modern Web Development:

These resources cover everything from basic web fundamentals to advanced modern development!

HTML/CSS/JavaScript Reference

Quick reference for HTML structure, CSS layouts, animations, and modern JavaScript features.

HTML Essentials
<!DOCTYPE html>\n<html lang="en">\n<head>\n    <meta charset="UTF-8">\n    <meta name="viewport" content="width=device-width, initial-scale=1.0">\n    <title>Page Title</title>\n</head>\n<body>\n    <h1>Hello World</h1>\n</body>\n</html>

Basic HTML5 document structure with responsive viewport

<header>\n    <nav>\n        <ul>\n            <li><a href="#home">Home</a></li>\n            <li><a href="#about">About</a></li>\n        </ul>\n    </nav>\n</header>\n<main>\n    <section id="home">\n        <h1>Welcome</h1>\n    </section>\n</main>\n<footer>\n    <p>&copy; 2025 My Website</p>\n</footer>

Semantic HTML structure with header, nav, main, section, and footer

<form action="/submit" method="post">\n    <label for="email">Email:</label>\n    <input type="email" id="email" name="email" required>\n    <label for="password">Password:</label>\n    <input type="password" id="password" name="password" required>\n    <button type="submit">Submit</button>\n</form>

Accessible form with labels, input validation, and proper attributes

CSS Layout & Flexbox
.container {\n    display: flex;\n    justify-content: space-between;\n    align-items: center;\n    gap: 1rem;\n    padding: 1rem;\n}

Flexbox container with spacing, alignment, and padding

.grid-container {\n    display: grid;\n    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));\n    gap: 1rem;\n    padding: 1rem;\n}

CSS Grid with responsive columns and automatic fitting

.responsive {\n    width: 100%;\n    max-width: 1200px;\n    margin: 0 auto;\n    padding: 0 1rem;\n}\n\n@media (max-width: 768px) {\n    .responsive {\n        padding: 0 0.5rem;\n    }\n}

Responsive container with media queries for mobile

CSS Styling & Effects
.button {\n    background: linear-gradient(45deg, #007bff, #0056b3);\n    color: white;\n    border: none;\n    padding: 0.75rem 1.5rem;\n    border-radius: 0.5rem;\n    cursor: pointer;\n    transition: transform 0.2s, box-shadow 0.2s;\n}\n\n.button:hover {\n    transform: translateY(-2px);\n    box-shadow: 0 4px 12px rgba(0, 123, 255, 0.3);\n}

Modern button with gradient, hover effects, and smooth transitions

.card {\n    background: white;\n    border-radius: 0.5rem;\n    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);\n    padding: 1.5rem;\n    margin: 1rem 0;\n}\n\n.card:hover {\n    box-shadow: 0 4px 20px rgba(0, 0, 0, 0.15);\n}

Card component with shadow and hover effects

@keyframes fadeIn {\n    from { opacity: 0; transform: translateY(20px); }\n    to { opacity: 1; transform: translateY(0); }\n}\n\n.fade-in {\n    animation: fadeIn 0.6s ease-out;\n}

CSS animations with keyframes for smooth entrance effects

JavaScript Fundamentals
// Variables and functions\nconst greeting = "Hello, World!";\nlet counter = 0;\n\nfunction increment() {\n    counter++;\n    console.log(`Counter: ${counter}`);\n}\n\n// Arrow function\nconst multiply = (a, b) => a * b;

Modern JavaScript syntax with const/let, template literals, and arrow functions

// DOM manipulation\nconst button = document.querySelector("#myButton");\nconst output = document.getElementById("output");\n\nbutton.addEventListener("click", () => {\n    output.textContent = "Button clicked!";\n    output.classList.add("highlight");\n});

DOM selection, event handling, and element manipulation

// Async/await with fetch\nasync function fetchData(url) {\n    try {\n        const response = await fetch(url);\n        const data = await response.json();\n        return data;\n    } catch (error) {\n        console.error("Error:", error);\n        throw error;\n    }\n}

Modern async JavaScript with fetch API and error handling

JavaScript DOM & Events
// Form handling\nconst form = document.querySelector("#myForm");\nform.addEventListener("submit", (e) => {\n    e.preventDefault();\n    const formData = new FormData(form);\n    const data = Object.fromEntries(formData);\n    console.log("Form data:", data);\n});

Form submission handling with FormData and preventDefault

// Dynamic content creation\nfunction createCard(title, content) {\n    const card = document.createElement("div");\n    card.className = "card";\n    card.innerHTML = `\n        <h3>${title}</h3>\n        <p>${content}</p>\n        <button onclick="removeCard(this)">Remove</button>\n    `;\n    return card;\n}

Dynamic HTML creation and element manipulation

// Local storage\nconst saveData = (key, value) => {\n    localStorage.setItem(key, JSON.stringify(value));\n};\n\nconst loadData = (key) => {\n    const item = localStorage.getItem(key);\n    return item ? JSON.parse(item) : null;\n};

Browser storage for persisting data between sessions

Modern JavaScript Features
// Destructuring and spread\nconst user = { name: "John", age: 30, email: "john@example.com" };\nconst { name, ...rest } = user;\n\nconst numbers = [1, 2, 3];\nconst moreNumbers = [...numbers, 4, 5];\n\n// Array methods\nconst doubled = numbers.map(n => n * 2);\nconst evens = numbers.filter(n => n % 2 === 0);

ES6+ features: destructuring, spread operator, and array methods

// Modules (ES6)\n// utils.js\nexport const formatDate = (date) => date.toLocaleDateString();\nexport default class Calculator {\n    add(a, b) { return a + b; }\n}\n\n// main.js\nimport Calculator, { formatDate } from "./utils.js";

ES6 modules with named and default exports/imports

// Promise handling\nPromise.all([\n    fetch("/api/users"),\n    fetch("/api/posts")\n])\n.then(responses => Promise.all(responses.map(r => r.json())))\n.then(([users, posts]) => {\n    console.log("Users:", users);\n    console.log("Posts:", posts);\n})\n.catch(console.error);

Advanced Promise handling with Promise.all for concurrent requests

Responsive Design
/* Mobile-first approach */\n.container {\n    padding: 1rem;\n}\n\n/* Tablet */\n@media (min-width: 768px) {\n    .container {\n        padding: 2rem;\n        max-width: 750px;\n        margin: 0 auto;\n    }\n}\n\n/* Desktop */\n@media (min-width: 1024px) {\n    .container {\n        max-width: 1200px;\n        padding: 3rem;\n    }\n}

Mobile-first responsive design with progressive enhancement

/* CSS Custom Properties (Variables) */\n:root {\n    --primary-color: #007bff;\n    --secondary-color: #6c757d;\n    --font-size-base: 1rem;\n    --border-radius: 0.5rem;\n}\n\n.button {\n    background-color: var(--primary-color);\n    font-size: var(--font-size-base);\n    border-radius: var(--border-radius);\n}

CSS custom properties for maintainable and themeable designs

Resources

MDN Web Docs

Comprehensive web technology documentation

HTML Living Standard

Official HTML specification

CSS Specifications

All CSS specifications

JavaScript Guide (MDN)

JavaScript fundamentals and modern features