JavaScript & TypeScript Editor: Write Modern Web Code
Edit JavaScript and TypeScript in the browser with Monaco, syntax highlighting, and run support. No install—perfect for snippets, learning, and quick API or regex tests.
✏️ JavaScript & TypeScript in the Browser—No Install
An online code editor that supports 40+ languages—including JavaScript and TypeScript—with the same engine as VS Code (Monaco). Write snippets, run JS or Python in the browser, format code, and share via link. Ideal for quick prototypes, learning, API or regex experiments, and sharing runnable examples without setting up a local IDE.
Why Use an Online JavaScript/TypeScript Editor?
Sometimes you need to run a snippet or try an idea without opening a full project. An in-browser editor helps when:
🚀Prototyping & Learning
- •Try ES6+, async/await, or TypeScript types without a build
- •Run JavaScript or Python and see output instantly
- •Share a link so others can open and run the same code
🔗Works With Other Tools
- •Paste curl output from our converter and run fetch/axios in the editor
- •Test regex from the Regex Tester, or format JSON and paste back
- •No install—works on any device with a modern browser
Using the Code Editor Tool
Our Code Editor gives you a full Monaco-based editor and optional execution. Step by step:
1Pick Language & Paste Code
Choose JavaScript, TypeScript, Python, or 40+ other languages from the dropdown. Paste or type code. Syntax highlighting and (where supported) IntelliSense work as you edit. Use the URL param ?lang=typescript to open in a specific language.
💡 Tip: Load a sample snippet from the language menu to get started quickly.
2Format & Run (JS/Python)
Click Format to pretty-print supported languages (JS, TS, JSON, HTML, CSS, etc.). For JavaScript and Python, click Run to execute in a sandbox. Output and errors appear in the panel beside the editor. Resize the panels by dragging the divider.
3Save or Share
Save the snippet to history with a name, or use Share to get a link. Anyone with the link can open the same code—handy for support, teaching, or code reviews. All editing and execution run in the browser; nothing is sent to our servers for running code.
JavaScript vs TypeScript in the Editor
Both are first-class in the tool. Choose based on what you're doing:
JavaScript
- • Dynamic typing—flexible, runs everywhere
- • No build step in the editor—run directly
- • Great for quick snippets and learning
Use when: prototyping, small scripts, or you want to run without transpilation.
TypeScript
- • Static types—catch errors before run
- • Interfaces, generics, union types
- • Better IntelliSense and refactoring
Use when: you want type safety or are pasting TS from a project. (Run executes JS; TS is type-checked in the editor.)
Modern JavaScript & TypeScript Examples
The editor supports ES6+, async/await, classes, and TypeScript. Quick examples:
JavaScript (ES6+ and async/await)
const greet = (name) => `Hello, ${name}!`;
async function fetchData() {
const res = await fetch('/api/data');
return res.json();
}TypeScript (interfaces and generics)
interface User { name: string; age: number; }
function getFirst<T>(items: T[]): T | undefined {
return items[0];
}Best Practices
Get the most out of the editor and keep code clean:
📏Prefer const/let and Modern Syntax
Use const by default and let when you need to reassign. Avoid var. Prefer arrow functions for callbacks and async/await over raw .then() chains so the Run output is easier to follow.
🖥️Use console.log for Run Output
When you click Run, console.log (and errors) appear in the output panel. Log the values you care about so you can debug without leaving the tool. For async code, make sure you await or .then() before logging.
🔒Don’t Paste Secrets
Execution runs in your browser, but if you share the link, anyone with it can see the code. Don’t paste API keys, passwords, or tokens into shared snippets. Use placeholders and add real secrets only in your local environment.
Common Pitfalls
Avoid these when writing or running code in the editor:
❌CORS and fetch in the Browser
If you run fetch('https://api.example.com') in the editor, the browser enforces CORS. Many APIs don’t allow requests from arbitrary origins. You’ll see CORS errors in the output. Use a public API that allows CORS, or test request shape with mock data.
⚠️TypeScript Run = JavaScript
The Run button executes JavaScript. TypeScript is type-checked in the editor but transpiled to JS for execution. So you get type errors in the editor, but at runtime it’s plain JS. For full TS builds, use a local project.
Pro Tips
Work faster with the editor and related tools:
🔗Chain With curl, JSON, and Regex
Convert a curl command in our curl Converter, paste the fetch/axios code into the editor, and run it. Paste API responses into the JSON Formatter. Test a regex in the Regex Tester, then use it in JS with new RegExp() in the editor.
📋Share Runnable Snippets
Use Share to get a link. Great for Stack Overflow answers, internal docs, or support—recipients open the link and can run the code without cloning a repo or installing anything.
✅ Write JavaScript & TypeScript in the Browser
Use our Code Editor to write and run JavaScript, TypeScript, Python, and 40+ other languages. Monaco-powered editing, format on demand, run in the browser, and share via link. Free, no sign-up, and your code stays in your browser until you share it.
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