# jposta

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[![npm downloads](https://img.shields.io/npm/dm/jposta.svg)](https://www.npmjs.com/package/jposta)
[![License: MIT](https://img.shields.io/badge/License-MIT-green.svg)](https://opensource.org/licenses/MIT)
[![TypeScript](https://img.shields.io/badge/TypeScript-007ACC?style=flat-square&logo=typescript&logoColor=white)](https://www.typescriptlang.org/)

Modern library for converting Japanese postal codes to addresses.
日本語の補足は最下部にあります。

## Features

⚡ Simple usage with compatibility for modern frameworks <br />
⚡ ES6 / Promise based / Typescript ready <br />
⚡ No dependencies <br />
⚡ Self-hosted & dynamic import (no implicit API calls)

## Installation

```bash
$ npm install jposta
```

## Usage

```javascript
import { getAddress } from "jposta";

// pass zip code as string
const address = await getAddress("1000001");
console.log(address);
// { pref: "東京都", prefNum: 13, city: "千代田区", area: "千代田" }

// also you can pass zip code with hyphen
const address2 = await getAddress("100-0003");
console.log(address2);
// { pref: "東京都", prefNum: 13, city: "千代田区", area: "皇居外苑" }
```

## Dynamic Import (Browser)

jposta requires hosting the data file in your project.

```bash
# Your project build
$ npm run build

> vite-react-jposta@0.0.0 build
> tsc && vite build

vite v5.2.13 building for production...
✓ 136 modules transformed.
dist/index.html                         0.46 kB │ gzip:  0.30 kB
dist/assets/react-CHdo91hT.svg          4.13 kB │ gzip:  2.05 kB
dist/assets/index-DiwrgTda.css          1.39 kB │ gzip:  0.72 kB
dist/assets/z11-nic1O4vt-B_L_y_VH.js    2.29 kB │ gzip:  0.95 kB
dist/assets/z96-Br2qdTMP-DG7Gpu3V.js   80.14 kB │ gzip: 27.45 kB
...(many files)
dist/assets/z50-BWUSdQBW-BJcxw7Xg.js   87.66 kB │ gzip: 29.14 kB
dist/assets/z60-34YubQWJ-DwuyaedM.js  101.50 kB │ gzip: 29.97 kB
dist/assets/index-D0vWSNxA.js         152.48 kB │ gzip: 49.62 kB
✓ built in 2.16s
```

...and then you can import the data file dynamically.

```javascript
const result1 = await getAddress("1000001");
// imports the data file named z10.js
const result2 = await getAddress("2100002");
// imports the data file named z21.js
const result3 = await getAddress("1000003");
// returns data without additional imports
```

## Compatibility

ESM & CJS compatible.
ESM is recommended.

## Samples

- Vite + React + jposta ([source code](https://github.com/nickichi/vite-react-jposta)):
  https://nickichi.github.io/vite-react-jposta/
- Next.js(webpack) + jposta ([source code](https://github.com/nickichi/nextjs-jposta)): https://nickichi.github.io/nextjs-jposta/
- Node.js + Express + jposta: https://github.com/nickichi/node-express-jposta

## License

see [LICENSE](./LICENSE)

---

## 補足

- 郵便番号と住所は、[日本郵便株式会社の郵便番号データ](https://www.post.japanpost.jp/zipcode/download.html)を利用しています
- このライブラリは self-hosted な郵便番号検索を提供するために作成されました。外部 API を使用せず、バックエンドも不要です。ただし、ホストするアセットが 100 個増えます。
- クライアントサイドでの Dynamic Import を利用したくない場合は、サーバサイド（Node.js）に導入することで、簡単に郵便番号 API を構築できます(Samples 参照)。