valid-email/lib/valid-email.js

Test the validity of an email address

/*!
 * Valid Email
 * Copyright(c) 2013 John Henry
 * MIT Licensed
 */

/**
 * Valid-Email:
 *
 * An alternative to using a regular expression to validate email.
 * Inspired by:
 *      http://stackoverflow.com/questions/997078/email-regular-expression
 *      http://stackoverflow.com/questions/201323/using-a-regular-expression-to-validate-an-email-address
 *
 * Examples:
 *     console.log(require('valid-email')('john@iamjohnhenry.com'))//#true
 *     console.log(require('valid-email')('iamjohnhenry.com'))//#false
 *
 * @param {String} email
 * // potential email address
 * @return {Boolean}
 * @api public
 */
module.exports = function valid(email) {
  if (!email) {
    return false; // email empty or undefined
  }
  var at = email.search("@");
  if (at < 0) {
    return false; // missing "@" symbol
  }
  var user = email.substr(0, at);
  var domain = email.substr(at + 1);
  var userLen = user.length;
  var domainLen = domain.length;
  if (userLen < 1 || userLen > 64) {
    return false; // user part length exceeded
  }
  if (domainLen < 1 || domainLen > 255) {
    return false; // domain part length exceeded
  }
  if (user.charAt(0) === "." || user.charAt(userLen - 1) === ".") {
    return false; // user part starts or ends with '.'
  }
  if (user.match(/\.\./)) {
    return false; // user part has two consecutive dots
  }
  if (!domain.match(/^[A-Za-z0-9.-]+$/)) {
    return false; // character not valid in domain part
  }
  if (domain.match(/\\.\\./)) {
    return false; // domain part has two consecutive dots
  }
  if (!user.match(/^[A-Za-z0-9!#%&`_=\\/$\'*+?^{}|~.\-" ]+$/)) {
    return false; // user part has invalid characters
  }
  return true;
};