validator.js

var validator = (function () {
  function trim(str) {
    return str.replace(/^\s+|\s+$/g, '');
  }

  function isEmail(field) {
    if (field) {
      var filter = /^([a-zA-Z0-9_\.\-])+\@(([a-zA-Z0-9\-])+\.)+([a-zA-Z0-9]{2,4})+$/;
      if (!filter.test(field)) {
        return false;
      } else {
        return true;
      }
    } else {
      return false;
    }
  }

  function isRequired(field) {
    if (field) {
      if (trim(field) === "") {
        return false;
      } else {
        return true;
      }
    } else {
      return false;
    }
  }

  function isNumber(field) {
    if (field) {
      var filter = /^[0-9]+$/;
      if (!filter.test(field + ''.replace(/ /gi, ''))) {
        return false;
      } else {
        return true;
      }
    } else {
      return false;
    }
  }
  return {
    isEmail: isEmail,
    isRequired: isRequired,
    isNumber: isNumber
  }
})();