nodejs why to use getters and setters code example

Example 1: getters and setters javascript

let obj = {
  log: ['a', 'b', 'c'],
  get latest() {
    if (this.log.length === 0) {
      return undefined;
    }
    return this.log[this.log.length - 1];
  }
};

obj.log.push('d');
console.log(obj.latest); //output: 'd'

Example 2: getter and setters in js

var person={firstname:"chetha",secondname="kumar",get fullname()
{
  	return this.firstname+" "+this.secondname;
}
document.write(person.fullname);
var person={firstname:"chethan",secondname="kumar",course:"",set course(x)
{
  	this.course=x;
}
person.course="bca";
document.write(person.course);