CloudInvaders/js/shooting_pad.js

const keys = {};

document.addEventListener('keydown', (e) => {
    keys[e.key] = true;
});
document.addEventListener('keyup', (e) => {
    keys[e.key] = false;
});

let blink = false;

setInterval(() => blink = !blink, 200);

const MAX_LIVES = 3;
const INVULNERABILITY_INTERVAL = 2000;

class ShootingPad extends Entity {
    constructor() {
        super(0.5, 0.95, 0.04, 0.03);
        const image = new Image();
        image.src = 'img/shooting-pad.svg';
        image.onload = () => this.image = image;

        this.lastShootTime = Date.now();
        this.invulnerable = false;
        this.lives = MAX_LIVES;
        this.initLives();
    }

    update() {
        if (keys['ArrowLeft'] || keys['a']) {
            this.x -= VELOCITY[0] * 2;
        }
        if (keys['ArrowRight'] || keys['d']) {
            this.x += VELOCITY[0] * 2;
        }
        if (this.x < X_BOUND) {
            this.x = X_BOUND;
        }
        if (this.x > 1 - X_BOUND) {
            this.x = 1 - X_BOUND;
        }
        if (keys[' '] && Date.now() - this.lastShootTime >= 300) {
            this.lastShootTime = Date.now();
            const bullet = new Bullet(this.x, this.y - 0.009);
            bullets.add(bullet);
        }
    }

    draw() {
        if (!this.invulnerable || blink) {
            super.draw();
        }
    }

    initLives() {
        $('#lives').textContent = `× ${this.lives}`;
    }

    lifeOver() {
        if (this.invulnerable) return;

        this.lives--;
        this.initLives();

        if (this.lives === 0) {
            return gameOver('Game over');
        } else {
            this.invulnerable = true;
            setTimeout(() => {
                this.invulnerable = false;
            }, INVULNERABILITY_INTERVAL);
        }
    }
}