index.js 1.1 KB

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  1. 'use strict';
  2. var hasSymbols = require('has-symbols')();
  3. var hasToStringTag = hasSymbols && typeof Symbol.toStringTag === 'symbol';
  4. var regexExec;
  5. var isRegexMarker;
  6. var badStringifier;
  7. if (hasToStringTag) {
  8. regexExec = Function.call.bind(RegExp.prototype.exec);
  9. isRegexMarker = {};
  10. var throwRegexMarker = function () {
  11. throw isRegexMarker;
  12. };
  13. badStringifier = {
  14. toString: throwRegexMarker,
  15. valueOf: throwRegexMarker
  16. };
  17. if (typeof Symbol.toPrimitive === 'symbol') {
  18. badStringifier[Symbol.toPrimitive] = throwRegexMarker;
  19. }
  20. }
  21. var toStr = Object.prototype.toString;
  22. var regexClass = '[object RegExp]';
  23. module.exports = hasToStringTag
  24. // eslint-disable-next-line consistent-return
  25. ? function isRegex(value) {
  26. if (!value || typeof value !== 'object') {
  27. return false;
  28. }
  29. try {
  30. regexExec(value, badStringifier);
  31. } catch (e) {
  32. return e === isRegexMarker;
  33. }
  34. }
  35. : function isRegex(value) {
  36. // In older browsers, typeof regex incorrectly returns 'function'
  37. if (!value || (typeof value !== 'object' && typeof value !== 'function')) {
  38. return false;
  39. }
  40. return toStr.call(value) === regexClass;
  41. };