6.1

// Your code here.
function Vector(x,y){
  this.x=x;
  this.y=y;
};
Vector.prototype.plus = function(vector){
  return new Vector(this.x+vector.x, this.y+vector.y)
}

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

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