validator.js

const _ = require('lodash');

const aMap = (obj) => _.isObject(obj);

const validator = (msg, aChecker) => {
  const f = function () {
    return aChecker.apply(aChecker, arguments);
  };
  f['msg'] = msg;
  return f;
  // aChecker.msg = msg;
  // return aChecker;
}

function hasKeys() {
  const keys = _.toArray(arguments);
  const f = (obj) => _.every(keys, key => _.has(obj, key));
  f.msg = _.concat('must have keys:', keys).join(' ');
  return f;
}

function validateWithRules() {
  const validators = _.toArray(arguments);

  return (obj) => {
    const errors = _.reduce(validators, (errors, validator) => {
      if (validator(obj)) {
        return errors;
      } else {
        return _.chain(errors).push(validator.msg).value();
      }
    }, []);
    console.log(errors);
    return errors;
  };
};

const validate = validateWithRules(
  validator('must be a map', aMap),
  hasKeys('msg', 'type')
);

validate({ msg: 'blah', type: 'display' });
validate(32);
validate({});