object-define-property.js

const myObject = {};

Object.defineProperty(myObject, "hi", {
  value: "mom",
  writable: true, // default: false
  enumerable: true, // default: false
  configurable: true, // default: false
});

console.log(myObject.hi); // > mom

myObject.hi = "medium";
console.log(myObject.hi); // > medium

delete myObject.hi;
console.log(myObject.hi); // > undefined

Object.defineProperty(myObject, "hi", {
  value: "mom",
  writable: true, // default: false
  enumerable: true, // default: false
  configurable: true, // default: false
});
console.log(myObject.hi); // > mom

Object.defineProperty(myObject, "hello", {
  value: "world",
  writable: false, // default: false
  enumerable: false, // default: false
  configurable: false, // default: false
});

console.log(myObject.hello); // > world

myObject.hello = "medium";
console.log(myObject.hello); // > world

delete myObject.hello;
console.log(myObject.hello); // > world

// > Uncaught TypeError: Cannot redefine property: hello at Function.defineProperty (<anonymous>)
Object.defineProperty(myObject, "hello", {
  value: "medium",
  writable: false, // default: false
  enumerable: false, // default: false
  configurable: false, // default: false
});
console.log(myObject.hello);