namae/availability/github.js

const fetch = require('isomorphic-unfetch')

async function getGitHubAvailability(name) {
  const githubURL = 'https://github.com'
  const response = await fetch(`${githubURL}/${encodeURIComponent(name)}`)
  return response.status === 404
}

module.exports = async (req, res) => {
  const name = req.query.name
  if (!name) {
    return res.status(400).json({ error: 'no query given' })
  }
  const availability = await getGitHubAvailability(name)
  res.json({ availability })
}