js判断域名是否存在

const dns = require('dns');

function checkDomainExists(domain, callback) {
  dns.resolve4(domain, (err, addresses) => {
    if (err) {
      callback(false);
    } else {
      callback(true);
    }
  });
}

checkDomainExists('example.com', (exists) => {
  console.log(exists ? 'Domain exists' : 'Domain does not exist');
});

const http = require('http');

function checkDomainExists(domain, callback) {
  http.get(`http://${domain}`, (res) => {
    callback(res.statusCode === 200);
  }).on('error', () => {
    callback(false);
  });
}

checkDomainExists('example.com', (exists) => {
  console.log(exists ? 'Domain exists' : 'Domain does not exist');
});