core-js/internals/set-method-get-keys-before-cloning-detection.js

Standard library

'use strict';
// Should get iterator record of a set-like object before cloning this
// https://bugs.webkit.org/show_bug.cgi?id=289430
module.exports = function (METHOD_NAME) {
  try {
    // eslint-disable-next-line es/no-set -- needed for test
    var baseSet = new Set();
    var setLike = {
      size: 0,
      has: function () { return true; },
      keys: function () {
        // eslint-disable-next-line es/no-object-defineproperty -- needed for test
        return Object.defineProperty({}, 'next', {
          get: function () {
            baseSet.clear();
            baseSet.add(4);
            return function () {
              return { done: true };
            };
          }
        });
      }
    };
    var result = baseSet[METHOD_NAME](setLike);

    return result.size !== 1 || result.values().next().value !== 4;
  } catch (error) {
    return false;
  }
};