RunKit + npm: jsdom

var jsdom = require("jsdom") var window = jsdom.jsdom().defaultView; function testDescriptor (obj) { Object.defineProperty(obj, 'testVar', {enumerable: true, get: function () { return 'test'; }}); console.log('get' in Object.getOwnPropertyDescriptor(obj, 'testVar')); } testDescriptor(global); // true (as expected) testDescriptor(window); // false (not expected) testDescriptor({}); // true (as expected)