namae/api/services/existence.ts

import { send, sendError, fetch, NowRequest, NowResponse } from '../util/http'

export default async function handler(req: NowRequest, res: NowResponse) {
  const { query } = req.query

  if (!query) {
    return sendError(res, new Error('no query given'))
  }

  if (
    !/^[(http(s)?):\/\/(www\.)?a-zA-Z0-9@:%._\+~#=]{2,256}\.[a-z]{2,6}\b([-a-zA-Z0-9@:%_\+.~#?&//=]*)$/.test(
      query
    )
  ) {
    return sendError(res, new Error('invalid characters'))
  }

  try {
    const response = await fetch(`https://${query}`)
    const availability = response.status === 404
    send(res, { availability })
  } catch (err) {
    sendError(res, err)
  }
}