var hasOwn = Object.prototype.hasOwnProperty; var toStr = Object.prototype.toString; var undefined; var isArray = function isArray(arr) { if (typeof Array.isArray === 'function') { return Array.isArray(arr); } return toStr.call(arr) === '[object Array]'; }; var isPlainObject = function isPlainObject(obj) { 'use strict'; if (!obj || toStr.call(obj) !== '[object Object]') { return false; } var has_own_constructor = hasOwn.call(obj, 'constructor'); var has_is_property_of_method = obj.constructor && obj.constructor.prototype && hasOwn.call(obj.constructor.prototype, 'isPrototypeOf'); // Not own constructor property must be Object if (obj.constructor && !has_own_constructor && !has_is_property_of_method) { return false; } // Own properties are enumerated firstly, so to speed up, // if last one is own, then all properties are own. var key; for (key in obj) {} return key === undefined || hasOwn.call(obj, key); }; module.exports = function extend() { 'use strict'; var options, name, src, copy, copyIsArray, clone, target = arguments[0], i = 1, length = arguments.length, deep = false; // Handle a deep copy situation if (typeof target === 'boolean') { deep = target; target = arguments[1] || {}; // skip the boolean and the target i = 2; } else if ((typeof target !== 'object' && typeof target !== 'function') || target == null) { target = {}; } for (; i < length; ++i) { options = arguments[i]; // Only deal with non-null/undefined values if (options != null) { // Extend the base object for (name in options) { src = target[name]; copy = options[name]; // Prevent never-ending loop if (target === copy) { continue; } // Recurse if we're merging plain objects or arrays if (deep && copy && (isPlainObject(copy) || (copyIsArray = isArray(copy)))) { if (copyIsArray) { copyIsArray = false; clone = src && isArray(src) ? src : []; } else { clone = src && isPlainObject(src) ? src : {}; } // Never move original objects, clone them target[name] = extend(deep, clone, copy); // Don't bring in undefined values } else if (copy !== undefined) { target[name] = copy; } } } } // Return the modified object return target; };