how to get property of javascript object code example

Example 1: javascript list object properties

var person={"first_name":"Bill","last_name":"Jenner"}
//get the person object properties with:
var keys = Object.keys(person); //keys = ["first_name","last_name"]

Example 2: 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";