gettersetter.js

function a () {
  var value = 1;
  
  return{
    get: function(){
      return value
    },
    set: function(n){
      value = n
      return value
    }
  } 
}
var aa = a()
console.log(aa.get())
console.log(aa.set(2))


var b = {
  value: 1,
  get: function(){
    return this.value
  },
  set: function(n){
    this.value = n
    return this.value
  }
}

console.log(b.get())
console.log(b.set(3))

var test = b.get
console.log(test())//throw an error