lodash/lodash.create/index.js

/**
 * lodash 4.0.2 (Custom Build) <https://lodash.com/>
 * Build: `lodash modularize exports="npm" -o ./`
 * Copyright 2012-2016 The Dojo Foundation <http://dojofoundation.org/>
 * Based on Underscore.js 1.8.3 <http://underscorejs.org/LICENSE>
 * Copyright 2009-2016 Jeremy Ashkenas, DocumentCloud and Investigative Reporters & Editors
 * Available under MIT license <https://lodash.com/license>
 */
var keys = require('lodash.keys');

/** Used for built-in method references. */
var objectProto = Object.prototype;

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

/** Built-in value references. */
var objectCreate = Object.create;

/**
 * Assigns `value` to `key` of `object` if the existing value is not equivalent
 * using [`SameValueZero`](http://ecma-international.org/ecma-262/6.0/#sec-samevaluezero)
 * for equality comparisons.
 *
 * @private
 * @param {Object} object The object to modify.
 * @param {string} key The key of the property to assign.
 * @param {*} value The value to assign.
 */
function assignValue(object, key, value) {
  var objValue = object[key];
  if ((!eq(objValue, value) ||
        (eq(objValue, objectProto[key]) && !hasOwnProperty.call(object, key))) ||
      (value === undefined && !(key in object))) {
    object[key] = value;
  }
}

/**
 * The base implementation of `_.assign` without support for multiple sources
 * or `customizer` functions.
 *
 * @private
 * @param {Object} object The destination object.
 * @param {Object} source The source object.
 * @returns {Object} Returns `object`.
 */
function baseAssign(object, source) {
  return object && copyObject(source, keys(source), object);
}

/**
 * The base implementation of `_.create` without support for assigning
 * properties to the created object.
 *
 * @private
 * @param {Object} prototype The object to inherit from.
 * @returns {Object} Returns the new object.
 */
function baseCreate(proto) {
  return isObject(proto) ? objectCreate(proto) : {};
}

/**
 * Copies properties of `source` to `object`.
 *
 * @private
 * @param {Object} source The object to copy properties from.
 * @param {Array} props The property names to copy.
 * @param {Object} [object={}] The object to copy properties to.
 * @returns {Object} Returns `object`.
 */
function copyObject(source, props, object) {
  return copyObjectWith(source, props, object);
}

/**
 * This function is like `copyObject` except that it accepts a function to
 * customize copied values.
 *
 * @private
 * @param {Object} source The object to copy properties from.
 * @param {Array} props The property names to copy.
 * @param {Object} [object={}] The object to copy properties to.
 * @param {Function} [customizer] The function to customize copied values.
 * @returns {Object} Returns `object`.
 */
function copyObjectWith(source, props, object, customizer) {
  object || (object = {});

  var index = -1,
      length = props.length;

  while (++index < length) {
    var key = props[index];

    var newValue = customizer
      ? customizer(object[key], source[key], key, object, source)
      : source[key];

    assignValue(object, key, newValue);
  }
  return object;
}

/**
 * Performs a [`SameValueZero`](http://ecma-international.org/ecma-262/6.0/#sec-samevaluezero)
 * comparison between two values to determine if they are equivalent.
 *
 * @static
 * @memberOf _
 * @category Lang
 * @param {*} value The value to compare.
 * @param {*} other The other value to compare.
 * @returns {boolean} Returns `true` if the values are equivalent, else `false`.
 * @example
 *
 * var object = { 'user': 'fred' };
 * var other = { 'user': 'fred' };
 *
 * _.eq(object, object);
 * // => true
 *
 * _.eq(object, other);
 * // => false
 *
 * _.eq('a', 'a');
 * // => true
 *
 * _.eq('a', Object('a'));
 * // => false
 *
 * _.eq(NaN, NaN);
 * // => true
 */
function eq(value, other) {
  return value === other || (value !== value && other !== other);
}

/**
 * Checks if `value` is the [language type](https://es5.github.io/#x8) of `Object`.
 * (e.g. arrays, functions, objects, regexes, `new Number(0)`, and `new String('')`)
 *
 * @static
 * @memberOf _
 * @category Lang
 * @param {*} value The value to check.
 * @returns {boolean} Returns `true` if `value` is an object, else `false`.
 * @example
 *
 * _.isObject({});
 * // => true
 *
 * _.isObject([1, 2, 3]);
 * // => true
 *
 * _.isObject(_.noop);
 * // => true
 *
 * _.isObject(null);
 * // => false
 */
function isObject(value) {
  var type = typeof value;
  return !!value && (type == 'object' || type == 'function');
}

/**
 * Creates an object that inherits from the `prototype` object. If a `properties`
 * object is given its own enumerable properties are assigned to the created object.
 *
 * @static
 * @memberOf _
 * @category Object
 * @param {Object} prototype The object to inherit from.
 * @param {Object} [properties] The properties to assign to the object.
 * @returns {Object} Returns the new object.
 * @example
 *
 * function Shape() {
 *   this.x = 0;
 *   this.y = 0;
 * }
 *
 * function Circle() {
 *   Shape.call(this);
 * }
 *
 * Circle.prototype = _.create(Shape.prototype, {
 *   'constructor': Circle
 * });
 *
 * var circle = new Circle;
 * circle instanceof Circle;
 * // => true
 *
 * circle instanceof Shape;
 * // => true
 */
function create(prototype, properties) {
  var result = baseCreate(prototype);
  return properties ? baseAssign(result, properties) : result;
}

module.exports = create;