firework.js

function Firework () {
    this.hu = random(255);
    this.firework = new Partical(random(width), height, this.hu, true)
    this.exploded = false;
    this.particles = [];

    this.isOffBound = function() {
        return this.firework.isOffbound()
    }

    this.done = function() {
        if (this.exploded && this.particles.length === 0) {
            return true
        } else {
            return false
        }
    }

    this.update = function() {
        if (!this.exploded) {
            this.firework.applyForce(gravity)
            this.firework.update()

            if (this.firework.vel.y >= 0) {
                this.exploded = true
                this.explode()
            }
        }
        for (var i = this.particles.length - 1; i >= 0; i--) {
            this.particles[i].applyForce(gravity)
            this.particles[i].update()
            if (this.particles[i].done()) {
                this.particles.splice(i, 1)
            }
        }
    }

    this.explode = function() {
        for (var i = 0; i < 100; i++) {
            var p = new Partical(this.firework.pos.x, this.firework.pos.y, this.hu, false)
            this.particles.push(p)
        }
    }

    this.show = function() {
        if (!this.exploded) {
            this.firework.show()
        } 
        for (var i = 0; i < this.particles.length; i++) {
            this.particles[i].show()
        }
    }
}