Practice task from "Eloquent Javascript"

vector.js

var Vector = function(x, y) {
  this.x = x;
  this.y = y;
}

Vector.prototype.plus = function(vector) {
  return new Vector.new(this.x + vector.x, this.y + vector.y)
}

Vector.prototype.minus = function(vector) {
  return new Vector.new(this.x - vector.x, this.y - vector.y)
}

Object.defineProperty(Vector.prototype, 'length', {
  get: function() {
    var ax = Math.pow(this.x, 2);
    var ay = Math.pow(this.y, 2);
    return Math.sqrt(ax + ay)
  }
});

console.log(new Vector(1, 2).plus(new Vector(2, 3)));
// Vector { x: 3, y: 5 }
console.log(new Vector(1, 2).minus(new Vector(2, 3)));
// Vector { x: -1, y: -1 }
console.log(new Vector(3, 4).length);
// 5