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Alex Spinov
Alex Spinov

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Bun Has a Free JavaScript Runtime That Replaces Node, npm, and Webpack

#bunjs #javascript #runtime #node

Bun is not just a runtime. It is a runtime + package manager + bundler + test runner + transpiler — all in one binary, all faster than the alternatives.

Speed Comparison

Task Node.js + tools Bun
Install deps (cold) npm: 30s bun: 3s
Install deps (cached) npm: 8s bun: 0.5s
Run TypeScript tsc + node: 2s bun: 0.1s
HTTP server (req/s) ~50K ~200K
Test runner jest: 15s bun test: 2s
Bundle webpack: 20s bun build: 1s

Install 

curl -fsSL https://bun.sh/install | bash
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Runtime 

// server.ts — runs directly, no build step
const server = Bun.serve({
  port: 3000,
  async fetch(req) {
    const url = new URL(req.url);

    if (url.pathname === "/api/users") {
      return Response.json([{ id: 1, name: "Alice" }]);
    }

    return new Response("Not Found", { status: 404 });
  },
});

console.log(`Listening on ${server.url}`);
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bun run server.ts
# TypeScript runs directly — no tsc, no ts-node
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Package Manager 

# 10-25x faster than npm
bun install              # Install all deps
bun add express          # Add package
bun add -d vitest        # Add dev dependency
bun remove express       # Remove package
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Bun uses a global cache and hardlinks — installs are nearly instant after the first time.

Bundler 

bun build ./src/index.ts --outdir ./dist --target browser --minify
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// Or programmatically
const result = await Bun.build({
  entrypoints: ["./src/index.ts"],
  outdir: "./dist",
  target: "browser",
  minify: true,
  splitting: true,
  sourcemap: "external",
});
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Test Runner 

// math.test.ts
import { test, expect, describe } from "bun:test";

describe("math", () => {
  test("adds numbers", () => {
    expect(1 + 2).toBe(3);
  });

  test("async operations", async () => {
    const response = await fetch("http://localhost:3000/api/users");
    expect(response.status).toBe(200);
    const data = await response.json();
    expect(data).toHaveLength(1);
  });
});
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bun test
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Jest-compatible API. 10x faster execution.

Built-in SQLite 

import { Database } from "bun:sqlite";

const db = new Database("app.db");

db.run(`CREATE TABLE IF NOT EXISTS users (
  id INTEGER PRIMARY KEY AUTOINCREMENT,
  name TEXT NOT NULL,
  email TEXT UNIQUE
)`);

const insert = db.prepare("INSERT INTO users (name, email) VALUES (?, ?)");
insert.run("Alice", "alice@test.com");

const users = db.query("SELECT * FROM users").all();
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Embedded SQLite — no npm package needed.

File I/O 

// Read
const content = await Bun.file("data.json").text();
const json = await Bun.file("data.json").json();
const buffer = await Bun.file("image.png").arrayBuffer();

// Write
await Bun.write("output.txt", "Hello World");
await Bun.write("data.json", JSON.stringify({ key: "value" }));

// Glob
const glob = new Bun.Glob("**/*.ts");
for await (const file of glob.scan("./src")) {
  console.log(file);
}
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npm Compatibility

Bun runs most npm packages. Express, React, Next.js, Prisma — all work.

bunx create-next-app@latest  # Works!
bunx prisma generate         # Works!
bunx vite                    # Works!
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Need high-performance JavaScript solutions? I build web tools and data pipelines. Email spinov001@gmail.com or check my Apify tools.

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