javascript how to check if object property exists

1if (obj.hasOwnProperty('prop')) {
2    // do something
3}

1const hero = {
2  name: 'Batman'
3};
4
5hero.hasOwnProperty('name');     // => true
6hero.hasOwnProperty('realName'); // => false

1var person = {'first_name': 'bill','age':20};
2
3if ( person.hasOwnProperty('first_name') ) {
4    //person has a first_name property
5}
6

1// the coolest way
2const obj = {
3 weather: 'Sunny; 
4}
5
6if('weather' in obj) {
7 // do something 
8}
9
10