how to add 2cdelete 2cupdate property in javascript object

1var brooklynNineNine = {
2  name: 'Raymond Holt',
3  currentRole: 'Captian of brooklyn99',
4}
5brooklynNineNine.husband = 'Kevin' // Or brooklynNineNine['husband'] = 'Kevin'
6
7var list =
8{
9  name: 'Michael Scott',
10  company: 'Dunder Mufflin',
11  designation: 'Regional Manager',
12  show: 'The Office',
13},
14  new_obj = { ...list, partner: 'Holly Flax' }
15
16var brooklynNineNine = {
17  name: 'Amy Santiago',
18  currentRole: 'Detective brooklyn99',
19  husband: 'Jake Peralta',
20  mentor: 'Raymond Holt'
21}
22
23delete brooklynNineNine.mentor;
24
25var favChar = {
26  name: 'Michael Scott',
27  company: 'Dunder Mufflin',
28  designation: 'Regional Manager',
29  show: 'The Office'
30}
31
32favChar.designation = 'Hero of Threat Level Midnight'