Why does the function returns 'undefined undefined' instead of name (James Bond)? Its a JS code [duplicate]

Question

function Person(first, last) {
    return {
        first: first,
        last: last,
        fullName: function() {
            return this.first + ' ' + this.last;
        },
        fullNameReversed: function() {
            return this.last + ', ' + this.first;
        }
    };
}
p = Person("James", "Bond");
var fullName = p.fullName;
fullName();

I was expecting Output = 'James Bond' but get 'undefined undefined'