function Person(first,last){
    var first = '', last = '';
  this.getName = function(){
      return this.first + ' ' + this.last;
  }
    this.setName = function(first,last){
        this.first = first;
        this.last = last;
    }
};
var person = new Person('John','Smith');
console.log(person);

var obj = {
    first: '',
    last: '',
    getName: function(first,last){
       return first + ' ' + last;
    },
    setName: function(first,last){
        this.first = first;
        this.last = last;
    }
}

obj.setName('John','Smith');