How to use the validator.isAlphanumeric function in validator

return function (req, res, next) {
    // make input not case sensitive
    req.body.username = req.body.username.toLowerCase();
    req.body.password = req.body.password.toLowerCase();

    if (
      validator.isAlphanumeric(req.body.username)
    ) {
      console.log("authentication = " + req.isAuthenticated());
      return next();
    }
    res.render("./auth/auth_register", {
      message: "Invalid input. Try again."
    })
  }
}

actions.createTable = async (payload, callback) => { // eslint-disable-line no-unused-vars
  const { contractName, tableName, indexes } = payload;
  let result = false;

  // check that the params are correct
  // each element of the indexes array have to be a string if defined
  if (validator.isAlphanumeric(tableName)
    && Array.isArray(indexes)
    && (indexes.length === 0
      || (indexes.length > 0 && indexes.every(el => typeof el === 'string' && validator.isAlphanumeric(el))))) {
    const finalTableName = `${contractName}_${tableName}`;
    // get the table from the database
    let table = await getCollection(finalTableName);
    if (table === null) {
      // if it doesn't exist, create it (with the binary indexes)
      await initSequence(finalTableName);
      await database.createCollection(finalTableName);
      table = database.collection(finalTableName);

      if (indexes.length > 0) {
        const nbIndexes = indexes.length;

        for (let i = 0; i < nbIndexes; i += 1) {

var validateTask = function (folderName, task) {
	var defer = Q.defer();

	var vn = (task.name || folderName);

	if (!task.id || !check.isUUID(task.id)) {
		defer.reject(createError(vn + ': id is a required guid'));
	};

	if (!task.name || !check.isAlphanumeric(task.name)) {
		defer.reject(createError(vn + ': name is a required alphanumeric string'));
	}

	if (!task.friendlyName || !check.isLength(task.friendlyName, 1, 40)) {
		defer.reject(createError(vn + ': friendlyName is a required string <= 40 chars'));
	}

	if (!task.instanceNameFormat) {
		defer.reject(createError(vn + ': instanceNameFormat is required'));
	}

	// resolve if not already rejected
	defer.resolve();
	return defer.promise;
};

result = validator.isAlpha('sample', 'hu-HU');
  result = validator.isAlpha('sample', 'nl-NL');
  result = validator.isAlpha('sample', 'pl-PL');
  result = validator.isAlpha('sample', 'pt-BR');
  result = validator.isAlpha('sample', 'pt-PT');
  result = validator.isAlpha('sample', 'ru-RU');
  result = validator.isAlpha('sample', 'sr-RS');
  result = validator.isAlpha('sample', 'sr-RS@latin');
  result = validator.isAlpha('sample', 'tr-TR');

  result = validator.isAlphanumeric('sample', 'ar');
  result = validator.isAlphanumeric('sample', 'ar-AE');
  result = validator.isAlphanumeric('sample', 'ar-BH');
  result = validator.isAlphanumeric('sample', 'ar-DZ');
  result = validator.isAlphanumeric('sample', 'ar-EG');
  result = validator.isAlphanumeric('sample', 'ar-IQ');
  result = validator.isAlphanumeric('sample', 'ar-JO');
  result = validator.isAlphanumeric('sample', 'ar-KW');
  result = validator.isAlphanumeric('sample', 'ar-LB');
  result = validator.isAlphanumeric('sample', 'ar-LY');
  result = validator.isAlphanumeric('sample', 'ar-MA');
  result = validator.isAlphanumeric('sample', 'ar-QA');
  result = validator.isAlphanumeric('sample', 'ar-QM');
  result = validator.isAlphanumeric('sample', 'ar-SA');
  result = validator.isAlphanumeric('sample', 'ar-SD');
  result = validator.isAlphanumeric('sample', 'ar-SY');
  result = validator.isAlphanumeric('sample', 'ar-TN');
  result = validator.isAlphanumeric('sample', 'ar-YE');
  result = validator.isAlphanumeric('sample', 'cs-CZ');
  result = validator.isAlphanumeric('sample', 'de-DE');
  result = validator.isAlphanumeric('sample', 'en-AU');
  result = validator.isAlphanumeric('sample', 'en-GB');

result = validator.isAlphanumeric('sample', 'ar');
  result = validator.isAlphanumeric('sample', 'ar-AE');
  result = validator.isAlphanumeric('sample', 'ar-BH');
  result = validator.isAlphanumeric('sample', 'ar-DZ');
  result = validator.isAlphanumeric('sample', 'ar-EG');
  result = validator.isAlphanumeric('sample', 'ar-IQ');
  result = validator.isAlphanumeric('sample', 'ar-JO');
  result = validator.isAlphanumeric('sample', 'ar-KW');
  result = validator.isAlphanumeric('sample', 'ar-LB');
  result = validator.isAlphanumeric('sample', 'ar-LY');
  result = validator.isAlphanumeric('sample', 'ar-MA');
  result = validator.isAlphanumeric('sample', 'ar-QA');
  result = validator.isAlphanumeric('sample', 'ar-QM');
  result = validator.isAlphanumeric('sample', 'ar-SA');
  result = validator.isAlphanumeric('sample', 'ar-SD');
  result = validator.isAlphanumeric('sample', 'ar-SY');
  result = validator.isAlphanumeric('sample', 'ar-TN');
  result = validator.isAlphanumeric('sample', 'ar-YE');
  result = validator.isAlphanumeric('sample', 'cs-CZ');
  result = validator.isAlphanumeric('sample', 'de-DE');
  result = validator.isAlphanumeric('sample', 'en-AU');
  result = validator.isAlphanumeric('sample', 'en-GB');
  result = validator.isAlphanumeric('sample', 'en-HK');
  result = validator.isAlphanumeric('sample', 'en-IN');
  result = validator.isAlphanumeric('sample', 'en-NZ');
  result = validator.isAlphanumeric('sample', 'en-US');
  result = validator.isAlphanumeric('sample', 'en-ZA');
  result = validator.isAlphanumeric('sample', 'en-ZM');
  result = validator.isAlphanumeric('sample', 'es-ES');
  result = validator.isAlphanumeric('sample', 'fr-FR');
  result = validator.isAlphanumeric('sample', 'fr-BE');

validateName: value =>
                ValidatorJS.isAlphanumeric(
                    value.replace(/\s|\.|\_|\-/g, ''),
                    'en-US'
                ),
            validateVendorName: value =>

if (!this.isNumeric(text) && !validator.isFloat(text)) {
                    is_valid = false;
                }
                break;
            case "decimal":
                if (!this.isNumeric(text) && !validator.isDecimal(text)) {
                    is_valid = false;
                }
                break;
            case "alpha":
                if (!validator.isAlpha(text)) {
                    is_valid = false;
                }
                break;
            case "alphanumeric":
                if (!validator.isAlphanumeric(text)) {
                    is_valid = false;
                }
                break;
        }

        if (validator.isEmpty(text)){
            is_valid = !(this.props.required);
        }

        return is_valid;
    }

validate: function () {
    let errors = {};
    if (!validator.isLowercase(this.state.username) || !validator.isAlphanumeric(this.state.username) || !validator.isLength(this.state.username, 4, 30)) {
      errors.username = 'Must be 4-30 lower case letters or numbers';
    }

    if (!validator.isLength(this.state.password, 5)) {
      errors.password = 'Must be at least 5 characters long';
    }

    if (!validator.isEmail(this.state.email)) {
      errors.email = 'Must be a valid email address';
    }
    return errors;
  },

function validateUsername(username) {
	return !validator.isEmpty(username) && validator.isAlphanumeric(username) && validator.isLength(username, {min: 4, max: 32});
}