SOURCE

'use strict'
let a = {name:'ykl'}
console.log(a)

let c = 18
Object.defineProperty(a,'age',{
    value: 22,
    writable:false,
    enumerable: true,
    configurable:false,

})


a.age = 1122
console.log(a.age)
console.log(Object.keys(a))
console.log(Object.entries(a))

Object.defineProperty(a,'age',{
    value: 22,
    writable:false,
    enumerable: true,
    configurable:false,

})
delete a.age;