Function isRegExp

test/expect.js:774–790

(re)

  }

  function isRegExp(re) {
    var s;
    try {
      s = '' + re;
    } catch (e) {
      return false;
    }

    return re instanceof RegExp || // easy case
           // duck-type for context-switching evalcx case
           typeof(re) === 'function' &&
           re.constructor.name === 'RegExp' &&
           re.compile &&
           re.test &&
           re.exec &&
           s.match(/^\/.*\/[gim]{0,3}$/);
  }

  function isDate(d) {
    return d instanceof Date;