core-js/internals/object-property-is-enumerable.js

Standard library

'use strict';
var nativePropertyIsEnumerable = {}.propertyIsEnumerable;
var nativeGetOwnPropertyDescriptor = Object.getOwnPropertyDescriptor;

// Nashorn ~ JDK8 bug
var NASHORN_BUG = nativeGetOwnPropertyDescriptor && !nativePropertyIsEnumerable.call({ 1: 2 }, 1);

exports.f = NASHORN_BUG ? function propertyIsEnumerable(V) {
  var descriptor = nativeGetOwnPropertyDescriptor(this, V);
  return !!descriptor && descriptor.enumerable;
} : nativePropertyIsEnumerable;