p5.js change object colour after X frames - p5.js

Question

I would like to change the fill colour of an object over time. Is there a way to change the fill colour of an object after X frames?
I am learning about constructors, and I am thinking that in the code's updateParticle function, after this.age counts to 'X', the fill colour of the ellipse could change.
'''
function Particle(x, y, xSpeed, ySpeed, size, colour) {
this.x = x;
this.y = y;
this.xSpeed = xSpeed;
this.ySpeed = ySpeed;
this.size = size;
this.colour = colour;
this.age = 0;
this.drawParticle = function() {
fill(this.colour);
noStroke();
ellipse(this.x, this.y, this.size);
}
this.updateParticle = function() {
this.x += this.xSpeed;
this.y += this.ySpeed;
this.age++;
}
}
function Emitter(x, y, xSpeed, ySpeed, size, colour) {
this.x = x;
this.y = y;
this.xSpeed = xSpeed;
this.ySpeed = ySpeed;
this.size = size;
this.colour = colour;
this.particles = [];
this.startParticles = [];
this.lifetime = 0;
this.addParticle = function() {
var p = new Particle(random(this.x - 10, this.x + 10),
random(this.y - 10, this.y + 10),
random(this.xSpeed - 0.4, this.xSpeed + 0.4),
random(this.ySpeed - 5, this.ySpeed - 1),
random(this.size - 4, this.size + 40),
this.colour);
return p;
}
this.startEmitter = function(startParticles, lifetime) {
this.startParticles = startParticles;
this.lifetime = lifetime;
for (var i = 0; i < startParticles; i++) {
this.particles.push(this.addParticle());
}
}
this.updateParticles = function() {
var deadParticles = 0
for (var i = this.particles.length - 1; i >= 0; i--) {
this.particles[i].drawParticle();
this.particles[i].updateParticle();
if (this.particles[i].age > random(0, this.lifetime)) {
this.particles.splice(i, 1);
deadParticles++;
}
}
if (deadParticles > 0) {
for (var i = 0; i < deadParticles; i++) {
this.particles.push(this.addParticle());
}
}
}
}
var emit;
function setup() {
createCanvas(800, 600);
emit = new Emitter(width / 2, height - 100, 0, -1, 10, color(200, 0, 200, 50));
emit.startEmitter(600, 4000);
}
function draw() {
background(200);
emit.updateParticles();
}
'''

Answer 1

Well you could just:
if(frameCount % 30 == 0){ // % 30 is the remainder of num / 30, so 4 % 3 = 1, since 3 / 3 = 0 And 4 / 3 = 3.33
fill("lime") // these are just preset colors in p5.js AND css lime == rgb(0,255,0)
} else {
fill('darkred')
}
or you could also do it with for example a switch statement: using background for no reason
switch(MY_frameCount){
case 1:
background('blue')
break
case 2:
background("darkgreen")
break
case 376:
background(crimson)
// break
}
MY_frameCount ++
or:
if(Math.random() < 0.1){
fill(Math.random() * 255, Math.random() * 255, Math.random() * 255)
} // this should on average fill with random color every 10 frames