create-web3/helpers/is-online.js

A boilerplate for creating a web3 projects

const { execSync } = require('child_process');
const dns = require('dns');
const url = require('url');

function getProxy() {
  if (process.env.https_proxy) {
    return process.env.https_proxy;
  }

  try {
    const httpsProxy = execSync('npm config get https-proxy').toString().trim();
    return httpsProxy !== 'null' ? httpsProxy : undefined;
  } catch (e) {
    return;
  }
}

const getOnline = () => {
  return new Promise((resolve) => {
    dns.lookup('registry.yarnpkg.com', (registryErr) => {
      if (!registryErr) {
        return resolve(true);
      }

      const proxy = getProxy();
      if (!proxy) {
        return resolve(false);
      }

      const { hostname } = url.parse(proxy);
      if (!hostname) {
        return resolve(false);
      }

      dns.lookup(hostname, (proxyErr) => {
        resolve(proxyErr == null);
      });
    });
  });
};

exports.getOnline = getOnline;