Hello, World!
console.log("Hello, World!");1 file
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main.js · output appears here
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Node.js 26.6.0Readymain.jsLn 1, Col 1Spaces: 4UTF-8
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main.js · output appears here
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Output streams here as your program runs.
JavaScript is a high-level, dynamically typed language originally created by Brendan Eich at Netscape in 1995 for adding interactivity to web pages. It is multi-paradigm, blending prototype-based object orientation, functional features like first-class functions and closures, and an event-driven model. The language is standardized as ECMAScript, with new editions adding features such as arrow functions, async/await, and modules.
Node.js, first released in 2009, brought JavaScript to the server by pairing the V8 engine with non-blocking I/O. Today server-side JavaScript powers web APIs, real-time apps, build tooling, and command-line utilities, with an enormous package ecosystem on npm. This compiler runs Node.js 26.6.0, executing scripts outside the browser, so DOM and window are not available but the full Node runtime and standard library are.
main.js is the entry point. Add helper files from the explorer and import them into your project.
Use the Input panel to pipe standard input to your program when it needs data.
Run sends your code to a fresh hosted runtime and streams the result into the output panel.
Your draft stays in this browser, and Share creates a separate snapshot link.
main.js imports an exported function from helper.js.
import { answer } from "./helper.js";
console.log(answer());
export function answer() {
return 42;
}
console.log("Hello, World!");const data = require("fs").readFileSync(0, "utf8").trim();
console.log(`Hello, ${data}!`);const fruits = ["apple", "banana", "cherry"];
fruits.forEach((fruit, i) => {
console.log(i + 1, fruit);
});function factorial(n) {
return n <= 1 ? 1 : n * factorial(n - 1);
}
console.log(factorial(5));try {
const obj = JSON.parse("{ bad json");
console.log(obj);
} catch (err) {
console.error("Parse failed:", err.message);
}const counts = new Map();
for (const ch of "banana") {
counts.set(ch, (counts.get(ch) || 0) + 1);
}
console.log([...counts.entries()]);
console.log(new Set([1, 1, 2, 3]));const s = " Hello, World ";
console.log(s.trim().toLowerCase());
console.log(s.trim().split(", "));
console.log(["a", "b", "c"].join("-"));class Person {
constructor(name, age) {
this.name = name;
this.age = age;
}
}
const people = [new Person("Ada", 36), new Person("Bob", 28)];
people.sort((a, b) => a.age - b.age);
people.forEach(p => console.log(p.name, p.age));const nums = [1, 2, 3, 4, 5];
const result = nums.filter(n => n % 2 === 1).map(n => n * n);
console.log(result);
console.log(nums.reduce((a, b) => a + b, 0));function delay(ms) {
return new Promise(resolve => setTimeout(resolve, ms));
}
async function main() {
await delay(10);
console.log("done");
}
main();The editor uses Monaco, the engine behind VS Code, with language-aware editing tools and familiar keyboard controls.
Type or paste your code into the editor, then click Run (or press Ctrl/Cmd + Enter) to execute it.
Output streams into the console panel, including runtime errors, exit status, and execution time.
Nothing to install and no account to create — code runs in an isolated hosted runtime.
Language-aware autocomplete and IntelliSense suggestions where the editor has a matching language service
Syntax highlighting, with native compiler and runtime errors shown in the console
Bracket matching, auto-indentation, code folding, and a minimap
Multi-cursor editing plus find & replace (Ctrl/Cmd + F)
Full undo/redo history and copy to clipboard
Built on Monaco — the same editor that powers VS Code
Run on demand, or turn on Auto-run to execute on every change
Stop long-running or infinite programs at any time
A real console shows standard output, errors, exit status, and execution time
Pass standard input (stdin) to your program from the Input panel — one value per line
Switch between light and dark themes
Adjust font size and other editor settings
Toggle side-by-side or top/bottom layouts
Enter distraction-free fullscreen mode
Generate a shareable link to your exact code in one click — no login needed
Your work autosaves to your browser, so you can pick up where you left off
Copy the active file to your clipboard
Run code: Ctrl/Cmd + Enter
Find & replace: Ctrl/Cmd + F
Open the full shortcut list from the keyboard icon in the toolbar
Node.js is one of 23 linked-project compilers. Run always starts main.js; selecting a helper tab changes what you edit, not the entry file.
main.js imports an exported function from helper.js.
Linked-project languages (23): Node.js, TypeScript, Deno, Python, C, Go, Dart, Swift, Rust, Ruby, PHP, Java, Kotlin, C++, C#, Nim, Crystal, Haxe, Zig, Scala, D, Bun, Objective-C.
Single-file scratchpads (46): Matplotlib, NumPy, pandas, Haskell, Clojure, Perl, Lua, Tcl, jq, Raku, Elixir, Bash, Zsh, Nushell, R, Assembly (NASM), Julia, Octave, Groovy, PowerShell, Visual Basic .NET, Odin, Pascal, Lisp, Erlang, CoffeeScript, COBOL, BASIC, V, Racket, OCaml, Prolog, AWK, Emacs Lisp, Emojicode, Forth, F#, Fortran, Assembly (NASM64), Solidity, Mojo, Ada, WASM (WAT), Gleam, Shell Script (sh), Scheme. Their extra project files are not submitted to the runtime.
Download project exports every Node.js tab and a README in one ZIP archive.