'use strict';

var isArray = Array.isArray; var keyList = Object.keys; var hasProp = Object.prototype.hasOwnProperty;

module.exports = function equal(a, b) {

if (a === b) return true;

if (a && b && typeof a == 'object' && typeof b == 'object') {
  var arrA = isArray(a)
    , arrB = isArray(b)
    , i
    , length
    , key;

  if (arrA && arrB) {
    length = a.length;
    if (length != b.length) return false;
    for (i = length; i-- !== 0;)
      if (!equal(a[i], b[i])) return false;
    return true;
  }

  if (arrA != arrB) return false;

  var dateA = a instanceof Date
    , dateB = b instanceof Date;
  if (dateA != dateB) return false;
  if (dateA && dateB) return a.getTime() == b.getTime();

  var regexpA = a instanceof RegExp
    , regexpB = b instanceof RegExp;
  if (regexpA != regexpB) return false;
  if (regexpA && regexpB) return a.toString() == b.toString();

  var keys = keyList(a);
  length = keys.length;

  if (length !== keyList(b).length)
    return false;

  for (i = length; i-- !== 0;)
    if (!hasProp.call(b, keys[i])) return false;

  for (i = length; i-- !== 0;) {
    key = keys[i];
    if (!equal(a[key], b[key])) return false;
  }

  return true;
}

return a!==a && b!==b;

};