custom Shake implementation for Phaser 2

Shake.ts

export class Shake {
	game: Phaser.Game;
	x: boolean;
	y: boolean;
	xoff: number;
	yoff: number;
	amp: number;
	tween: Phaser.Tween;

	constructor(game: Phaser.Game) {
		this.game = game;
	}

	shake(amp: number, duration: number, x: boolean, y?: boolean) {
		this.reset();

		this.x = x;
		this.y = !x && y === undefined? true: y; 
		this.amp = amp;

		this.tween = this.game.add.tween(this);
		this.tween.to({amp: 0}, duration, Phaser.Easing.Linear.None, true);
	}

	reset() {
		this.restore();
		this.xoff = 0;
		this.yoff = 0;
		this.amp = 0;
		if (this.tween) {
			this.tween.stop();
			this.tween = null;
		}
	}

	private restore() {
		if (this.x) this.game.camera.x -= this.xoff;
		if (this.y) this.game.camera.y -= this.yoff;
	}

	update() {
		if (!this.amp) {
			return;
		}

		this.restore();

		if (this.x) {
			this.xoff = Math.round(this.game.rnd.realInRange(-this.amp, this.amp));
			this.game.camera.x += this.xoff;
		}
		if (this.y) {
			this.yoff = Math.round(this.game.rnd.realInRange(-this.amp, this.amp));
			this.game.camera.y += this.yoff;
		}
	}
}