Extract TLD list JSON from IANA database

build-tld-list.js

/**
 * Requirements:
 *  - Node v10
 *  - punycode.js
 */

const request = require('request');
const punycode = require('punycode');

const tldDbUrl = 'https://data.iana.org/TLD/tlds-alpha-by-domain.txt';

// wrap a request in an promise
function downloadPage(url) {
  return new Promise((resolve, reject) => {
      request(url, (error, response, body) => {
          if (error) reject(error);
          if (response.statusCode != 200) {
              reject('Invalid status code <' + response.statusCode + '>');
          }
          resolve(body);
      });
  });
}

async function main() {
  const content = await downloadPage(tldDbUrl);
  const result = [];
  const items = content.split('\n')
  delete items[0];
  delete items[items.length - 1];
  items.forEach(item => {
    if (item.startsWith('XN--')) {
      result.push(punycode.decode(item.substr(4)))
    } else {
      result.push(item)
    }
  })
  console.table(JSON.stringify(result))
}

main();