extend.js 2.3 KB

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  1. // https://github.com/justmoon/node-extend
  2. // SPDX-License-Identifier: MIT
  3. 'use strict';
  4. var hasOwn = Object.prototype.hasOwnProperty;
  5. var toStr = Object.prototype.toString;
  6. var isArray = function isArray(arr) {
  7. if (typeof Array.isArray === 'function') {
  8. return Array.isArray(arr);
  9. }
  10. return toStr.call(arr) === '[object Array]';
  11. };
  12. var isPlainObject = function isPlainObject(obj) {
  13. if (!obj || toStr.call(obj) !== '[object Object]') {
  14. return false;
  15. }
  16. var hasOwnConstructor = hasOwn.call(obj, 'constructor');
  17. var hasIsPrototypeOf = obj.constructor && obj.constructor.prototype && hasOwn.call(obj.constructor.prototype, 'isPrototypeOf');
  18. // Not own constructor property must be Object
  19. if (obj.constructor && !hasOwnConstructor && !hasIsPrototypeOf) {
  20. return false;
  21. }
  22. // Own properties are enumerated firstly, so to speed up,
  23. // if last one is own, then all properties are own.
  24. var key;
  25. for (key in obj) { /**/ }
  26. return typeof key === 'undefined' || hasOwn.call(obj, key);
  27. };
  28. module.exports = function extend() {
  29. var options, name, src, copy, copyIsArray, clone;
  30. var target = arguments[0];
  31. var i = 1;
  32. var length = arguments.length;
  33. var deep = false;
  34. // Handle a deep copy situation
  35. if (typeof target === 'boolean') {
  36. deep = target;
  37. target = arguments[1] || {};
  38. // skip the boolean and the target
  39. i = 2;
  40. } else if ((typeof target !== 'object' && typeof target !== 'function') || target == null) {
  41. target = {};
  42. }
  43. for (; i < length; ++i) {
  44. options = arguments[i];
  45. // Only deal with non-null/undefined values
  46. if (options != null) {
  47. // Extend the base object
  48. for (name in options) {
  49. src = target[name];
  50. copy = options[name];
  51. // Prevent never-ending loop
  52. if (target !== copy) {
  53. // Recurse if we're merging plain objects or arrays
  54. if (deep && copy && (isPlainObject(copy) || (copyIsArray = isArray(copy)))) {
  55. if (copyIsArray) {
  56. copyIsArray = false;
  57. clone = src && isArray(src) ? src : [];
  58. } else {
  59. clone = src && isPlainObject(src) ? src : {};
  60. }
  61. // Never move original objects, clone them
  62. target[name] = extend(deep, clone, copy);
  63. // Don't bring in undefined values
  64. } else if (typeof copy !== 'undefined') {
  65. target[name] = copy;
  66. }
  67. }
  68. }
  69. }
  70. }
  71. // Return the modified object
  72. return target;
  73. };