How can I add firstName and lastName to fullName?

Question

person = { firstName: 'Joseph', lastName: 'Magnolia', ageInYears: 34 }

function addFullName(personObj) {
  person = { fullName: firstName + lastName, ageInYears: 34, }
}

It tells me undefined, and I have tried different things.

Answer 1

your code doesn't really make any sense, but did you mean something like this:

var person = { firstName: 'Joseph', lastName: 'Magnolia', ageInYears: 34 };
addFullName(person);
console.log(person);

function addFullName(personObj) {
      personObj.fullName = personObj.firstName + ' ' + personObj.lastName;
    }