vector.js

class vector {
  constructor() {
    this._x = 1;
    this._y = 0;
  }

  static create(x, y) {
    var obj = new vector();
    obj.setX(x);
    obj.setY(y);
    return obj;
  }

  setX(value) {
    this._x = value;
  }
  getX() {
    return this._x;
  }

  setY(value) {
    this._y = value;
  }
  getY() {
    return this._y;
  }

  setAngle(angle) {
    let length = this.getLength();
    this._x = Math.cos(angle) * length;
    this._y = Math.sin(angle) * length;
  }
  getAngle() {
      console.log('angle to ', Math.atan2(this._y, this._x)*(180/Math.PI));
    return Math.atan2(this._y, this._x);
  }

  setLength(length) {
    let angle = this.getAngle();
    this._x = Math.cos(angle) * length;
    this._y = Math.sin(angle) * length;
  }
  getLength() {
    return Math.sqrt(this._x * this._x + this._y * this._y);
  }

  add(v2) {
    return vector.create(this._x + v2.getX(), this._y + v2.getY());
  }

  subtract(v2) {
    return vector.create(this._x - v2.getX(), this._y - v2.getY());
  }

  //scalar multiplication
  multiply(val) {
    return vector.create(this._x *val, this._y *val);
  }

  //scalar division
  divide(val) {
    return vector.create(this._x/val, this._y/val);
  }

  addTo(v2) {
   this._x+=v2.getX();
   this._y+=v2.getY();
  }

  subtractFrom(v2) {
    this._x-=v2.getX();
    this._y-=v2.getY();
   }

  //scalar multiplication
  multiplyTo(val) {
    this._x*=val;
    this._y*=val;
  }

  //scalar division
  divideFrom(val) {
    this._x/=val;
    this._y/=val;
  }
}