ParticleSystem.ts

class Particle {
  constructor(x, y) {
    this.pos = new Vector2(x, y);
    this.vel = new Vector2(Math.random(), Math.random());
  }

update() {
this.pos.add(this.vel);
if (this.pos.x > width || this.pos.x < 0) this.vel.x _= -1;
if (this.pos.y > height || this.pos.y < 0) this.vel.y _= -1;
}
}