index.js

/*!
 * is-plain-object <https://github.com/jonschlinkert/is-plain-object>
 *
 * Copyright (c) 2014-2017, Jon Schlinkert.
 * Released under the MIT License.
 */

'use strict';

var isObject = require('isobject');

function isObjectObject(o) {
  return isObject(o) === true
    && Object.prototype.toString.call(o) === '[object Object]';
}

module.exports = function isPlainObject(o) {
  var ctor,prot;

  if (isObjectObject(o) === false) return false;

  // If has modified constructor
  ctor = o.constructor;
  if (typeof ctor !== 'function') return false;

  // If has modified prototype
  prot = ctor.prototype;
  if (isObjectObject(prot) === false) return false;

  // If constructor does not have an Object-specific method
  if (prot.hasOwnProperty('isPrototypeOf') === false) {
    return false;
  }

  // Most likely a plain Object
  return true;
};