var h = window.innerHeight; 

var stars = [];

​

function setup() {

  canvas=createCanvas(w, h);

    for (var i = 0; i < 1000; i++) {

        stars[i] = new Star();

    }

}

​

function draw() {

  background(0);

    for (var i = 0; i < stars.length; i++) {

        stars[i].draw();

    }

​

}

​

window.onresize = function() {

  // assigns new values for width and height variables

  w = window.innerWidth;

  h = window.innerHeight;  

  canvas.size(w,h);

}

// star class //

class Star {

    constructor() {

        this.x = random(w);

        this.y = random(h);

        this.size = random(0.25, 3);

        this.t = random(TAU);

    }

    draw() {

        this.t += 0.1;

        var scale = this.size + sin(this.t) * 2;

        noStroke();

        ellipse(this.x, this.y, scale, scale);

    }

}