index.js 2.3 KB

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  1. 'use strict';
  2. var isCallable = require('is-callable');
  3. var toStr = Object.prototype.toString;
  4. var hasOwnProperty = Object.prototype.hasOwnProperty;
  5. /** @type {<This, A extends readonly unknown[]>(arr: A, iterator: (this: This | void, value: A[number], index: number, arr: A) => void, receiver: This | undefined) => void} */
  6. var forEachArray = function forEachArray(array, iterator, receiver) {
  7. for (var i = 0, len = array.length; i < len; i++) {
  8. if (hasOwnProperty.call(array, i)) {
  9. if (receiver == null) {
  10. iterator(array[i], i, array);
  11. } else {
  12. iterator.call(receiver, array[i], i, array);
  13. }
  14. }
  15. }
  16. };
  17. /** @type {<This, S extends string>(string: S, iterator: (this: This | void, value: S[number], index: number, string: S) => void, receiver: This | undefined) => void} */
  18. var forEachString = function forEachString(string, iterator, receiver) {
  19. for (var i = 0, len = string.length; i < len; i++) {
  20. // no such thing as a sparse string.
  21. if (receiver == null) {
  22. iterator(string.charAt(i), i, string);
  23. } else {
  24. iterator.call(receiver, string.charAt(i), i, string);
  25. }
  26. }
  27. };
  28. /** @type {<This, O>(obj: O, iterator: (this: This | void, value: O[keyof O], index: keyof O, obj: O) => void, receiver: This | undefined) => void} */
  29. var forEachObject = function forEachObject(object, iterator, receiver) {
  30. for (var k in object) {
  31. if (hasOwnProperty.call(object, k)) {
  32. if (receiver == null) {
  33. iterator(object[k], k, object);
  34. } else {
  35. iterator.call(receiver, object[k], k, object);
  36. }
  37. }
  38. }
  39. };
  40. /** @type {(x: unknown) => x is readonly unknown[]} */
  41. function isArray(x) {
  42. return toStr.call(x) === '[object Array]';
  43. }
  44. /** @type {import('.')._internal} */
  45. module.exports = function forEach(list, iterator, thisArg) {
  46. if (!isCallable(iterator)) {
  47. throw new TypeError('iterator must be a function');
  48. }
  49. var receiver;
  50. if (arguments.length >= 3) {
  51. receiver = thisArg;
  52. }
  53. if (isArray(list)) {
  54. forEachArray(list, iterator, receiver);
  55. } else if (typeof list === 'string') {
  56. forEachString(list, iterator, receiver);
  57. } else {
  58. forEachObject(list, iterator, receiver);
  59. }
  60. };