clone.js

var baseClone = require('../internal/baseClone'),
    bindCallback = require('../internal/bindCallback'),
    isIterateeCall = require('../internal/isIterateeCall');

/**
 * Creates a clone of `value`. If `isDeep` is `true` nested objects are cloned,
 * otherwise they are assigned by reference. If `customizer` is provided it is
 * invoked to produce the cloned values. If `customizer` returns `undefined`
 * cloning is handled by the method instead. The `customizer` is bound to
 * `thisArg` and invoked with two argument; (value [, index|key, object]).
 *
 * **Note:** This method is loosely based on the
 * [structured clone algorithm](http://www.w3.org/TR/html5/infrastructure.html#internal-structured-cloning-algorithm).
 * The enumerable properties of `arguments` objects and objects created by
 * constructors other than `Object` are cloned to plain `Object` objects. An
 * empty object is returned for uncloneable values such as functions, DOM nodes,
 * Maps, Sets, and WeakMaps.
 *
 * @static
 * @memberOf _
 * @category Lang
 * @param {*} value The value to clone.
 * @param {boolean} [isDeep] Specify a deep clone.
 * @param {Function} [customizer] The function to customize cloning values.
 * @param {*} [thisArg] The `this` binding of `customizer`.
 * @returns {*} Returns the cloned value.
 * @example
 *
 * var users = [
 *   { 'user': 'barney' },
 *   { 'user': 'fred' }
 * ];
 *
 * var shallow = _.clone(users);
 * shallow[0] === users[0];
 * // => true
 *
 * var deep = _.clone(users, true);
 * deep[0] === users[0];
 * // => false
 *
 * // using a customizer callback
 * var el = _.clone(document.body, function(value) {
 *   if (_.isElement(value)) {
 *     return value.cloneNode(false);
 *   }
 * });
 *
 * el === document.body
 * // => false
 * el.nodeName
 * // => BODY
 * el.childNodes.length;
 * // => 0
 */
function clone(value, isDeep, customizer, thisArg) {
  if (isDeep && typeof isDeep != 'boolean' && isIterateeCall(value, isDeep, customizer)) {
    isDeep = false;
  }
  else if (typeof isDeep == 'function') {
    thisArg = customizer;
    customizer = isDeep;
    isDeep = false;
  }
  return typeof customizer == 'function'
    ? baseClone(value, isDeep, bindCallback(customizer, thisArg, 1))
    : baseClone(value, isDeep);
}

module.exports = clone;