Bun Online Compiler

Write, Run & Share Bun code online using OneCompiler's Bun online compiler for free. It's one of the fastest, feature-rich online compilers for the Bun runtime. Getting started with OneCompiler's Bun editor is easy and fast. The editor shows sample boilerplate code when you choose Bun as the language and start coding.

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About Bun

Bun is a modern JavaScript runtime designed for speed, efficiency, and native support for modern web development. It is built on JavaScriptCore instead of V8, making it extremely fast for running JavaScript and TypeScript applications.

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Key Features

• Blazing fast: Bun is significantly faster than Node.js and Deno for many operations.
• Built-in package manager: No need for npm or yarn—Bun can install packages directly.
• Native TypeScript & JSX support: No additional configuration required.
• Embedded SQLite & Web APIs: Makes it easy to build full-stack applications.
• Compatible with Node.js APIs: Supports many existing Node.js modules.

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Syntax Help

Hello World

console.log("Hello, World!");

Variable Declaration

Keyword	Description	Scope
var	Old way of declaring variables	Function or global
let	Block-scoped variable	Block scope
const	Constant, cannot be reassigned	Block scope

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Arrow Functions

Arrow functions provide a more concise syntax for defining functions.

Syntax:

const greet = (name: string): string => `Hello, ${name}!`;
console.log(greet("Bun"));

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Template Literals (Backtick Strings)

Interpolation

let name = "Bun";
console.log(`Hello, ${name}!`);

Multi-line Strings

const message = `
Hello,
Welcome to Bun!
`;
console.log(message);

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Arrays

An array is a collection of values.

Syntax:

let numbers: number[] = [1, 2, 3, 4, 5];
console.log(numbers[0]); // Accessing first element

Spread operator with Arrays

let moreNumbers = [...numbers, 6, 7, 8];
console.log(moreNumbers);

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Object Destructuring

Example:

const user = { name: "Alice", age: 25 };
const { name, age } = user;
console.log(name, age);

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Loops

For Loop

for (let i = 0; i < 5; i++) {
  console.log(i);
}

While Loop

let count = 0;
while (count < 5) {
  console.log(count);
  count++;
}

Do-While Loop

let num = 0;
do {
  console.log(num);
  num++;
} while (num < 5);

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Classes

Bun supports ES6 classes, allowing for object-oriented programming.

Example:

class Car {
  model: string;

  constructor(model: string) {
    this.model = model;
  }

  display(): void {
    console.log(`Car model: ${this.model}`);
  }
}

const myCar = new Car("Tesla");
myCar.display();

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Bun’s Built-in HTTP Server

Unlike Node.js, Bun has a simplified HTTP server API.

Example:

import { serve } from "bun";

serve({
  port: 3000,
  fetch(req) {
    return new Response("Hello, World from Bun!");
  },
});

console.log("Server running at http://localhost:3000");

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Bun is an exciting alternative to Node.js, optimized for speed and modern JavaScript/TypeScript development! 🚀