How to copy an Object in Javascript?

Any change made in captain object will also reflect in person object.

const person = { name: 'Wes Bos', age: 80 };
console.log(person);
//{name: "Wes Bos", age: 80}
const captain = person;
console.log(captain);
//{name: "Wes Bos", age: 80}
person.age = 90;
console.log(captain);
// {name: "Wes Bos", age: 90} 

See We didn't even made any change to captin but the changes made to person object reflects on captain object as well.
This is because captain is not a copy of person object but it is rather a reference to the person object.
So Any change made in captain object will also reflect in person object.

const cap2 = Object.assign({},person,{age:12,number:99});
console.log(cap2);
const cap3 = {...person};
console.log(cap3);