Bun & TypeScriptでバックエンド開発入門：基本的な実行環境の構築手順まとめ

$ curl -fsSL <https://bun.sh/install> | bash

# 一度ターミナルを再起動

$ bun --version
1.0.29

# brewコマンドの場合
$ brew install oven-sh/bun/bun

# npmコマンドの場合
$ npm install -g bun

$ bun init                                                                                                                                                                                                         21:48:19
bun init helps you get started with a minimal project and tries to guess sensible defaults. Press ^C anytime to quit

package name (ts-bun-template): 
entry point (index.ts): 

Done! A package.json file was saved in the current directory.
 + index.ts
 + .gitignore
 + tsconfig.json (for editor auto-complete)
 + README.md

To get started, run:
  bun run index.ts

.
├── node_modules/
├── README.md
├── bun.lockb
├── index.ts
├── package.json
└── tsconfig.json

{
  "name": "ts-bun-template",
  "module": "index.ts",
  "type": "module",
  "devDependencies": {
    "@types/bun": "^1.0.8"
  },
  "peerDependencies": {
    "typescript": "^5.0.0"
  }
}

{
  "compilerOptions": {
    // Enable latest features
    "lib": ["ESNext"],
    "target": "ESNext",
    "module": "ESNext",
    "moduleDetection": "force",
    "jsx": "react-jsx",
    "allowJs": true,

    // Bundler mode
    "moduleResolution": "bundler",
    "allowImportingTsExtensions": true,
    "verbatimModuleSyntax": true,
    "noEmit": true,

    // Best practices
    "strict": true,
    "skipLibCheck": true,
    "noFallthroughCasesInSwitch": true,

    // Some stricter flags (disabled by default)
    "noUnusedLocals": false,
    "noUnusedParameters": false,
    "noPropertyAccessFromIndexSignature": false
  }
}

const server = Bun.serve({
  port: 3000,
  fetch(req) {
    return new Response("Bun!");
  },
});

console.log(`Listening on http://localhost:${server.port} ...`);

$ bun run index.ts
Listening on http://localhost:3000 ...

$ curl http://localhost:3000
Bun!

$ bun pm ls
/Users/gorida/Github/ts-bun-template node_modules (7)
├── @types/bun@1.0.8
└── typescript@5.4.2


$ bun pm ls --all
/Users/gorida/Github/ts-bun-template node_modules
├── @types/bun@1.0.8
├── @types/node@20.11.25
├── @types/ws@8.5.10
├── bun-types@1.0.29
├── typescript@5.4.2
└── undici-types@5.26.5

$ bun pm cache
/Users/gorida/.bun/install/cache

$ bun pm cache rm
Cache directory deleted:
  /Users/daikigoto/.bun/install/cache

{
  "name": "ts-bun-template",
  "module": "index.ts",
  "type": "module",
  "scripts": {
    "start": "bun run index.ts",
    "start:watch": "bun run --watch index.ts",
    "start:hot": "bun run --hot index.ts"
  },
  "devDependencies": {
    "@types/bun": "^1.0.8"
  },
  "peerDependencies": {
    "typescript": "^5.0.0"
  }
}

declare global {
  var items: string[];
}

globalThis.items ??= []; // itemsが未定義の場合、空の配列で初期化

const server = Bun.serve({
  port: 3000,
  fetch(req) {
    // リクエストごとに配列にアイテムを追加
    globalThis.items.push(`Item${globalThis.items.length + 1}`);
    return new Response(`Items: ${globalThis.items.join(", ")}`);
  },
});

console.log(`Listening on http://localhost:${server.port} ...`);

$ curl http://localhost:3000
Items: Item1

$ curl http://localhost:3000
Items: Item1, Item2
                                                                      
$ curl http://localhost:3000
Items: Item1, Item2, Item3

#ここでindex.tsのconsole.log内を更新
#サーバーが再起動される

$ curl http://localhost:3000
（更新後）Items: Item1

#Items内が初期化されている

$ curl http://localhost:3000
Items: Item1

$ curl http://localhost:3000
Items: Item1, Item2
                                                                      
$ curl http://localhost:3000
Items: Item1, Item2, Item3

#ここでindex.tsのconsole.log内を更新

$ curl http://localhost:3000
（更新後）Items: Item1, Item2, Item3, Item4

#Items内が継続してItem4が追加されている