js property assignment delete

1let person = {
2  firstname: 'John',
3  lastname: 'Doe'
4}
5
6console.log(person.firstname);
7// expected output: "John"
8
9delete person.firstname;
10
11console.log(person.firstname);
12// expected output: undefined

1delete objectName['Property Name'];
2delete objectName.propName;

1delete obj.firstname;