JAVASCRIPT

Add New Properties to a JavaScript Object

var myDog = {
  "name": "Happy Coder",
  "legs": 4,
  "tails": 1,
  "friends": ["freeCodeCamp Campers"]
};

myDog.bark = "woof";
// or
myDog["bark"] = "woof";

javascript Adding Properties And Methods in an Object

// constructor function
function Person () {
    this.name = 'John',
    this.age = 23
}
// creating objects
let person1 = new Person();
let person2 = new Person();
// adding property to person1 object
person1.gender = 'male';
// adding method to person1 object
person1.greet = function () {
    console.log('hello');
}
person1.greet();   // hello

// Error code
// person2 doesn't have greet() method
person2.greet();