arcade physics/distance to pointer

 
var game = new Phaser.Game(800, 600, Phaser.CANVAS, 'phaser-example', { preload: preload, create: create, update: update, render: render });

function preload() {

    game.load.image('backdrop', 'assets/pics/remember-me.jpg');
    game.load.image('ball', 'assets/sprites/shinyball.png');

}

var ball;
var cursors;

function create() {

    game.physics.startSystem(Phaser.Physics.ARCADE);

    game.world.setBounds(0, 0, 1920, 1200);

    game.add.sprite(0, 0, 'backdrop');

    ball = game.add.sprite(game.world.randomX, 200, 'ball');

    game.physics.arcade.enable(ball);

    game.camera.follow(ball);

    cursors = game.input.keyboard.createCursorKeys();

}

function update() {

    ball.body.velocity.x = 0;
    ball.body.velocity.y = 0;

    if (cursors.left.isDown)
    {
        ball.body.velocity.x = -240;
    }
    else if (cursors.right.isDown)
    {
        ball.body.velocity.x = 240;
    }

    if (cursors.up.isDown)
    {
        ball.body.velocity.y = -240;
    }
    else if (cursors.down.isDown)
    {
        ball.body.velocity.y = 240;
    }

}

function render() {

    game.debug.text("Distance to pointer: " + game.physics.arcade.distanceToPointer(ball), 32, 32);

}