kakao

index.js

const axios = require('axios');
const { send, sendError } = require('micro');
const { URL, URLSearchParams } = require('url');

const KAKAO_APP_KEY = 'YOUR_KAKAO_APP_KEY';
const KAKAO_REDIRECT_URL = 'http://www.lvh.me:3000/authorize/callback';

const KAKAO_AUTHORIZE_ENDPOINT = (() => {
  const url = new URL('https://kauth.kakao.com/oauth/authorize');

  url.searchParams.append('client_id', KAKAO_APP_KEY);
  url.searchParams.append('redirect_uri', KAKAO_REDIRECT_URL);
  url.searchParams.append('response_type', 'code');

  return url.toString();
})();

module.exports = exports = async (req, res) => {
  const pathname = parsePathname(req.url);

  if (pathname === '/authorize') {
    return redirect(res, KAKAO_AUTHORIZE_ENDPOINT);
  }


  if (pathname === '/authorize/callback') {
    const query = parseQuery(req.url);
    const code = query.get('code');

    if (!code) {
      return redirect(res, KAKAO_AUTHORIZE_ENDPOINT);
    }

    try {
      const params = new URLSearchParams(new Map([
        ['grant_type', 'authorization_code'],
        ['client_id', KAKAO_APP_KEY],
        ['redirect_url', KAKAO_REDIRECT_URL],
        ['code', code],
      ]));

      const res = await axios({
        method: 'POST',
        url: 'https://kauth.kakao.com/oauth/token',
        headers: {
          'Content-Type': 'application/x-www-form-urlencoded',
        },
        data: params.toString(),
      });

      return res.data;
    } catch (e) {
      if (e.response) {
        console.error('Request failed with %d', e.response.status, e.response.data);
      }

      return sendError(req, res, e);
    }
  }


  return redirect(res, '/authorize');
}

function parsePathname(url) {
  const index = url.indexOf('?');
  return index === -1 ? url : url.slice(0, index);
}

function parseQuery(url) {
  const index = url.indexOf('?');

  if (index === -1) {
    return new URLSearchParams();
  }

  return new URLSearchParams(url.slice(index + 1));
}

function redirect(res, location, status = 302) {
  res.setHeader('Location', location);
  return send(res, status);
}

package.json

{
  "name": "kakao-oauth",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "author": "",
  "license": "ISC",
  "dependencies": {
    "axios": "^0.18.0",
    "micro": "^9.3.3"
  }
}