Practice front-end web development with this free online HTML, CSS, and JavaScript code playground. Edit, preview, and test code in real-time effortlessly.
AI Generation Prompt
Project Overview
This application is a lightweight, high-performance, in-browser front-end development environment. It allows users to write raw HTML, CSS, and JavaScript and view the rendered output instantly in a sandboxed iframe. The design is strictly a professional, light-mode interface with no dark mode and no footer.
Core Features
- Real-time Rendering: The output iframe updates automatically as the user types, using a debounce function to prevent performance bottlenecks.
- Tri-Pane Editor: Three distinct text areas for HTML, CSS, and JavaScript, displayed as columns on desktop and stacked on mobile.
- Syntax Highlighting: Integrated lightweight syntax highlighting for readability without requiring heavy frameworks.
- Sandboxed Execution: The output runs within an
iframewith thesandboxattribute to ensure security. - Import/Export: Functional buttons to clear all code, copy code to the clipboard, and download the current state as a standard .html file.
- Console Logging (Optional): A simulated console overlay to help users debug JS errors without opening dev tools.
UI/UX Design
- Layout: A clean header containing the title and utility buttons (Clear, Copy, Download). The body consists of three flexible editors (HTML, CSS, JS) and a large, full-width preview pane below.
- Color Palette: A clean, professional aesthetic using a #FFFFFF background, #F8F9FA for editor containers, and #007BFF for primary buttons. Border lines should be #DEE2E6.
- Typography: System-stack fonts (Inter, sans-serif) for high readability.
- Responsiveness: The app must utilize Flexbox and CSS Grid to ensure it functions perfectly on mobile devices, tablets, and desktops. No scrolling issues on small screens.
- Interactions: Subtle, fast hover states on buttons and a smooth transition when toggling pane layouts.
Technical Implementation
- Single File: The entire application must be contained within a single
index.htmlfile, including CSS in<style>tags and JS in<script>tags. - No External Dependencies: Minimize reliance on external dependencies. If needed, use CDN links, but prefer vanilla JS implementations for editor logic.
- Sandboxing: The preview window MUST use an
iframewith thesrcdocattribute to inject user-provided code securely. - Constraints:
- Strictly NO dark mode.
- Strictly NO footer content.
- Must be fully mobile-responsive.
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Files being used
Frequently Asked Questions
Everything you need to know about using this application.
Can I save my work using this tool?
This application runs entirely in your local browser. To save your work, you can copy the code manually or use your browser's print functionality to save the current state.
Does this code playground work offline?
Yes, once the application is loaded in your browser, it works entirely client-side without requiring an active internet connection.
Are external libraries supported?
Yes, you can include external CSS or JavaScript libraries by adding the appropriate CDN links directly into the HTML section.
