ExplosionGroup subclass of Phaser.Group for #LOWREZJAM

ExplosionGroup.js

function ExplosionGroup(game) {
    // Call the Phaser.Group constructor
    Phaser.Group.call(this, game);
    // Have the game add this group
    this.game.add.existing(this);
}

ExplosionGroup.prototype = Object.create(Phaser.Group.prototype);
ExplosionGroup.prototype.constructor = ExplosionGroup;

ExplosionGroup.prototype.explode = function(x, y) {
    // Get the first 'dead' member of the group
    var explosion = this.getFirstDead();

    // If 'explosion' is null, there weren't any 'dead' memebers
    if (explosion === null) {
        // Create a sprite using the 'explosion' cache key
        explosion = this.game.add.sprite(0, 0, 'explosion');
        // Center its anchor
        explosion.anchor.setTo(0.5, 0.5);
        // Create an animation based on the 'explosion' cache key
        //  and label it 'boom' for later playing.
        //  (We also need to save a reference to the create animation.)
        var animation = explosion.animations.add('boom', [0, 1, 2, 3], 50, false);
        // Tell the animation to kill() itself when done
        animation.killOnComplete = true;
        // All the sprite + animation to the group
        this.add(explosion);
    }
    // If there was a 'dead' member in the group, revive it.
    //  Otherwise, 'revive' the new member.
    explosion.revive();
    // Reset its position to those passed into this function
    explosion.reset(x, y);
    // Pick a random angle for the sprite (and thus animation)
    explosion.angle = this.game.rnd.integerInRange(0, 360);
    // Play the 'boom' animation.
    // (When it is done, it will kill the animation.)
    explosion.animations.play('boom');
};