const object1 = new Object(); object1.property1 = 42; console.log(object1.hasOwnProperty('property1')); // expected output: true
var person = {'first_name': 'bill','age':20}; if ( person.hasOwnProperty('first_name') ) { //person has a first_name property }
const hero = { name: 'Batman' }; hero.hasOwnProperty('name'); // => true hero.hasOwnProperty('realName'); // => false