correct way to declare object in js code example

Example 1: js objects

// To make an object literal:
const dog = {
    name: "Rusty",
    breed: "unknown",
    isAlive: false,
    age: 7
}
// All keys will be turned into strings!

// To retrieve a value:
dog.age; //7
dog["age"]; //7

//updating values
dog.breed = "mutt";
dog["age"] = 8;

Example 2: how to create object js

function person(fname, lname, age, eyecolor){
  this.firstname = fname;
  this.lastname = lname;
  this.age = age;
  this.eyecolor = eyecolor;
}

myFather = new person("John", "Doe", 50, "blue");
document.write(myFather.firstname + " is " + myFather.age + " years old.");