dog6.js

function Dog(name) {
 this.name = name;
 this.bark = function () {
  console.log("Guau!")
 }
}
let d = []
for(let i = 0; i<1000000; i++) {
  d[i] = new Dog(i)
}
console.log(d.length)

dog7.js

function Dog(name) {
 this.name = name;
}
Dog.prototype.bark = function () {
  console.log("Guau!")
 }
let d = []
for(let i = 0; i<1000000; i++) {
  d[i] = new Dog(i)
}
console.log(d.length)