lodash/lodash.isplainobject/index.js

/**
 * lodash 3.0.2 (Custom Build) <https://lodash.com/>
 * Build: `lodash modern modularize exports="npm" -o ./`
 * Copyright 2012-2015 The Dojo Foundation <http://dojofoundation.org/>
 * Based on Underscore.js 1.8.3 <http://underscorejs.org/LICENSE>
 * Copyright 2009-2015 Jeremy Ashkenas, DocumentCloud and Investigative Reporters & Editors
 * Available under MIT license <https://lodash.com/license>
 */
var baseFor = require('lodash._basefor'),
    isNative = require('lodash.isnative'),
    keysIn = require('lodash.keysin');

/** `Object#toString` result references. */
var objectTag = '[object Object]';

/**
 * Checks if `value` is object-like.
 *
 * @private
 * @param {*} value The value to check.
 * @returns {boolean} Returns `true` if `value` is object-like, else `false`.
 */
function isObjectLike(value) {
  return !!value && typeof value == 'object';
}

/** Used for native method references. */
var objectProto = Object.prototype;

/** Used to check objects for own properties. */
var hasOwnProperty = objectProto.hasOwnProperty;

/**
 * Used to resolve the [`toStringTag`](https://people.mozilla.org/~jorendorff/es6-draft.html#sec-object.prototype.tostring)
 * of values.
 */
var objToString = objectProto.toString;

/** Native method references. */
var getPrototypeOf = isNative(getPrototypeOf = Object.getPrototypeOf) && getPrototypeOf;

/**
 * The base implementation of `_.forIn` without support for callback
 * shorthands and `this` binding.
 *
 * @private
 * @param {Object} object The object to iterate over.
 * @param {Function} iteratee The function invoked per iteration.
 * @returns {Object} Returns `object`.
 */
function baseForIn(object, iteratee) {
  return baseFor(object, iteratee, keysIn);
}

/**
 * A fallback implementation of `_.isPlainObject` which checks if `value`
 * is an object created by the `Object` constructor or has a `[[Prototype]]`
 * of `null`.
 *
 * @private
 * @param {*} value The value to check.
 * @returns {boolean} Returns `true` if `value` is a plain object, else `false`.
 */
function shimIsPlainObject(value) {
  var Ctor;

  // Exit early for non `Object` objects.
  if (!(isObjectLike(value) && objToString.call(value) == objectTag) ||
      (!hasOwnProperty.call(value, 'constructor') &&
        (Ctor = value.constructor, typeof Ctor == 'function' && !(Ctor instanceof Ctor)))) {
    return false;
  }
  // IE < 9 iterates inherited properties before own properties. If the first
  // iterated property is an object's own property then there are no inherited
  // enumerable properties.
  var result;
  // In most environments an object's own properties are iterated before
  // its inherited properties. If the last iterated property is an object's
  // own property then there are no inherited enumerable properties.
  baseForIn(value, function(subValue, key) {
    result = key;
  });
  return result === undefined || hasOwnProperty.call(value, result);
}

/**
 * Checks if `value` is a plain object, that is, an object created by the
 * `Object` constructor or one with a `[[Prototype]]` of `null`.
 *
 * **Note:** This method assumes objects created by the `Object` constructor
 * have no inherited enumerable properties.
 *
 * @static
 * @memberOf _
 * @category Lang
 * @param {*} value The value to check.
 * @returns {boolean} Returns `true` if `value` is a plain object, else `false`.
 * @example
 *
 * function Foo() {
 *   this.a = 1;
 * }
 *
 * _.isPlainObject(new Foo);
 * // => false
 *
 * _.isPlainObject([1, 2, 3]);
 * // => false
 *
 * _.isPlainObject({ 'x': 0, 'y': 0 });
 * // => true
 *
 * _.isPlainObject(Object.create(null));
 * // => true
 */
var isPlainObject = !getPrototypeOf ? shimIsPlainObject : function(value) {
  if (!(value && objToString.call(value) == objectTag)) {
    return false;
  }
  var valueOf = value.valueOf,
      objProto = isNative(valueOf) && (objProto = getPrototypeOf(valueOf)) && getPrototypeOf(objProto);

  return objProto
    ? (value == objProto || getPrototypeOf(value) == objProto)
    : shimIsPlainObject(value);
};

module.exports = isPlainObject;