Live Code Editor – Write & Preview HTML, CSS, JS

CodePen-inspired Code Editor

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Mastering the CodePen-inspired Online Code Editor: Your Web Development Sandbox

CodePen has long been a favorite among developers for its intuitive split-pane interface, allowing real-time editing of HTML, CSS, and JavaScript with an instant live preview. The CodePen-inspired Online Code Editor recreates this experience in your browser, offering a vibrant, modern tool to code, style, and see your web creations come to life. Perfect for developers prototyping designs, students learning front-end skills, or hobbyists experimenting with code, this editor combines power and simplicity—no account required. Let’s dive into its features, how it works, and why it’s a must-have for web development enthusiasts.

What Is the CodePen-inspired Online Code Editor?

This Online Code Editor is a browser-based tool modeled after CodePen, featuring separate panels for HTML, CSS, and JavaScript, a live preview that updates as you type, and options to format and save your work as a single HTML file. It’s a sandbox for web development, letting you craft interactive snippets with the same split-pane ease that CodePen users love—without needing an external platform.

The design is fresh and eye-catching—a dark slate gradient background pairs with sleek, color-coded panels (pink for HTML, yellow for CSS, blue for JS) and gradient buttons, all optimized for readability. It scales to 80% width on desktops and 100% on mobile, ensuring a smooth experience anywhere. It’s your personal CodePen, right at your fingertips.

How Does It Work?

The editor replicates CodePen’s workflow with a twist. You get three panels: HTML, CSS, and JavaScript. Type your HTML (e.g., `

Hello

`) in the pink panel, add CSS (e.g., `.box { color: white; background: black; }`) in the yellow panel, and write JavaScript (e.g., `document.querySelector(".box").textContent = "Hi";`) in the blue panel. As you edit any panel, the live preview updates instantly below, rendering your HTML with applied CSS and executed JS—matching CodePen’s real-time magic.

Click “Format All” to clean up your code—HTML gets indented, CSS and JS get basic line breaks—making it easier to read, just like CodePen’s formatting tools. Hit “Save as HTML” to download a single .html file with your HTML, CSS (in a ` ${html} `; // Use a Blob and iframe srcdoc for reliable live preview const blob = new Blob([fullHtml], { type: 'text/html' }); const url = URL.createObjectURL(blob); preview.innerHTML = ``; URL.revokeObjectURL(url); // Clean up after rendering status.textContent = 'Preview Updated'; status.style.color = '#4ADE80'; } catch (e) { preview.innerHTML = `

Error: ${e.message}

`; status.textContent = `Error: ${e.message}`; status.style.color = '#FF4500'; } } function formatAll() { const htmlInput = document.getElementById('html-input'); const cssInput = document.getElementById('css-input'); const jsInput = document.getElementById('js-input'); const status = document.getElementById('status'); try { htmlInput.value = formatHtmlCode(htmlInput.value); cssInput.value = formatCssCode(cssInput.value); jsInput.value = formatJsCode(jsInput.value); updatePreview(); status.textContent = 'All Code Formatted Successfully'; status.style.color = '#4ADE80'; } catch (e) { status.textContent = `Error formatting: ${e.message}`; status.style.color = '#FF4500'; } } function formatHtmlCode(html) { let indentLevel = 0; const indentSize = 2; let result = ''; let inTag = false; let buffer = ''; html = html.replace(/\s+/g, ' ').trim(); for (let char of html) { if (char === '<') { if (buffer.trim()) { result += ' '.repeat(indentLevel * indentSize) + buffer.trim() + '\n'; } buffer = char; inTag = true; } else if (char === '>') { buffer += char; inTag = false; if (buffer.startsWith('$/) && !buffer.match(/ ${html} `; const blob = new Blob([fullHtml], { type: 'text/html' }); const url = URL.createObjectURL(blob); const a = document.createElement('a'); a.href = url; a.download = 'project.html'; a.click(); URL.revokeObjectURL(url); } // Initial preview updatePreview();

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