Field of parallaxed stars - Phaser

parallaxStars.js

var game = new Phaser.Game("100", "100", Phaser.AUTO, '', { preload: preload, create: create, update: update });

var random = new Phaser.RandomDataGenerator()

function preload() {
    game.load.image("star", "star1.png")
}

function create() {
    game.world.setBounds(-1500, -1500, 3000, 3000)

    stars = game.add.group()

    for (var i = 0; i < 1000; i++) {
        star = game.add.sprite(0, 0, "star")
        star.depth = random.realInRange(1,10)
        star.worldPos = {x: random.realInRange(-1500 * star.depth, 1500 * star.depth), y: random.realInRange(-1500 * star.depth, 1500 * star.depth)}
        scale = 1 / star.depth
        star.scale.set(scale, scale)
        stars.add(star)
        star.position.x = star.worldPos.x
        star.position.y = star.worldPos.y
    }
}

function update() {
    stars.forEach(function(star) {
        star.position.x = (star.worldPos.x - (game.camera.x + (game.camera.width / 2))) / star.depth
        star.position.y = (star.worldPos.y - (game.camera.y + (game.camera.height / 2))) / star.depth
    })
    game.camera.setPosition(game.input.x - (game.camera.width), game.input.y - (game.camera.height))
}