Combining classes and instance mode in p5js?

p5.js Coding Questions
1

Hi recently I came across the topic of running sketches in p5js in an instance mode. I had been able to draw shapes and do basic visualization using the instance mode. However I am quite confused when it comes in dealing with classes and instance mode. For example I am trying to simulate particles , using instance mode. How is the syntax usually with classes when dealing with the instance mode? For example the particle system is defined in particle.js as follows.

class Particle {
  constructor() {
    this.pos = p5.createVector(0,0,0);
    this.vel = p5.Vector.random3D().normalize().mult(random(4,6));
  }
  
  update() {
    this.p.pos.add(this.vel);
  }
  draw(){
    push();
    noStroke();
    fill(255);
    translate(this.pos.x,this.pos.y,this.pos.z);
    box(10,10,10);
    pop()
  }
}
2