Processing p5.js + Javascript ES6 Test Sketch

p5_es6_class_test.js

// Javascript ES6 Class Test
// Works in Chrome and p5 on OS X.
'use strict';

let rays,
    nRays = 1000;

class DisplayableList extends Array {
    constructor() {
        super();
    }

    update() {
        this.forEach(function(item) {
            item.update();
        })
    }

    display() {
        this.forEach(function(item) {
            item.display();
        })
    }
}

class Ray {
    constructor(position, velocity) {
        this.position = position;
        this.velocity = velocity;
    }

    update() {
        this.position.add(this.velocity);
    }

    display() {
        let p2 = this.position.copy().sub(this.velocity.copy().mult(4));
        line(this.position.x, this.position.y, p2.x, p2.y);
    }
}

function init() {
    rays = new DisplayableList();
    let start_position = createVector(random(width), random(height));
    for (let i = 0; i < nRays; i++) {
        let position = start_position.copy(),
            velocity = p5.Vector.fromAngle(random(TAU)).mult(random(0.25, 4)),
            ray = new Ray(position, velocity);
        rays.push(ray);
    }
}

function setup() {
    createCanvas(500, 500);
    init();
    stroke(255, 32, 32, 128);
}

function draw() {
    if (frameCount % 120 === 0) {
        init();
    }
    blendMode(BLEND);
    background(0);
    blendMode(ADD);
    rays.update();
    rays.display();
}