/** * Check if a sub-domain is valid * @param {String} hostname sub-domain * @returns {Boolean} true if valid */ const isValidHost = (hostname) => { if (typeof hostname !== 'string') { return false; } const regex = /^[\dA-Za-z]([\dA-Za-z-]{0,61}[\dA-Za-z])?$/; return regex.test(hostname); }; module.exports = { isValidHost, };