JavaScript Playground: Run JavaScript, HTML and CSS
Write and run JavaScript, HTML, and CSS in a sandboxed iframe with a live console output panel and preview. Network access is blocked by a CSP meta tag by default; you can toggle it on with a visible warning. Use auto-run mode to run code as you work, or Stop/Reset to recreate the iframe and break an infinite loop. Starter examples help you get started.
JavaScript Playground is a browser-based coding workspace for writing and running JavaScript, HTML, and CSS. The editor has separate JS, HTML, and CSS tabs, with a preview pane and live console output panel so you can inspect a page and its output together. Use it to experiment with a short snippet or try code without installing a local development environment.
Code runs inside a sandboxed iframe configured with allow-scripts and no allow-same-origin. A CSP meta tag blocks network access by default; you can toggle it on, and the interface displays a visible warning. Auto-run mode runs code as you work. If a script gets stuck in an infinite loop, Stop/Reset destroys and recreates the iframe. Starter examples are also included.
JavaScript, HTML, and CSS have different roles in a web page: HTML structures content, CSS controls its presentation, and JavaScript adds behavior. Keeping them in separate tabs makes it easier to test how these parts work together, review a change in the preview, and check output in the console.
The JavaScript Playground runs entirely in your browser. Your input is processed on your device and is not uploaded, stored, or sent to a server. It works offline once the page has loaded, and it is free to use. Developers and DevOps engineers can use it to explore code, check page behavior, or work through a quick programming task from different machines.
Step 1: Open the JS, HTML, and CSS tabs and enter the code you want to try. Use the relevant tab for each part of your page.
Step 2: Choose whether to use auto-run mode. When enabled, your code runs automatically as you work.
Step 3: Keep the default network protection in mind: a CSP meta tag blocks network access. You can toggle network access on, and the playground displays a visible warning.
Step 4: Run your code and inspect the preview and live console output panel to see the results.
Step 5: If code gets stuck in an infinite loop, use Stop/Reset to destroy and recreate the sandboxed iframe.
Use case: Try a JavaScript snippet without installing a local development environment. The playground runs your code in the browser and shows live console output.
Use case: Check how HTML, CSS, and JavaScript work together by editing them in their separate tabs and reviewing the preview.
Use case: Investigate code behavior with the live console output panel alongside the page preview.
Use case: Recover from an infinite loop by using Stop/Reset to destroy and recreate the iframe.
Use case: Work on a programming task from a machine where you do not have a local setup available.
Use case: Avoid sending internal code or data to a third-party service: the playground processes input in your browser.
Use case: Explore the starter examples when you want a starting point for experimenting with JavaScript, HTML, or CSS.