Generate Items with delay in phaser3

I'm creating a simple game in phaser, where I have a spaceship, which by pressing the space bar, shoots projectiles. This is the code:

var gameScene = new Phaser.Scene('game');
var navicella;
var bullets; 

gameScene.preload = function(){
    this.load.image('navicella', './assets/astronave.png')
    this.load.image('bullet', './assets/bullet.png')
}

gameScene.create = function(){
    navicella = this.physics.add.sprite(450, 500, 'navicella');
    bullets = this.physics.add.group();
    this.keySpace = this.input.keyboard.addKey(Phaser.Input.Keyboard.Key.SPACE, 100);
    
}
gameScene.update = function(){
    navicella.x = this.input.mousePointer.x;
    if(this.keySpace.isDown){
        var bullet = bullets.create(navicella.x, 500, 'bullet');
        bullet.setVelocityY(-100);
        
    }

    
}
var config = {
    type: Phaser.AUTO,
    width: 900, 
    height: 600,
    scene: gameScene,
    physics: {
        default: 'arcade',
        arcade: {
            debug: false,
            gravity:{y: 0}
        }
    },
};
var game = new Phaser.Game(config);

The problem in the code, is that when I press the space bar, too many projectiles are generated, there is no limit. I had thought about adding a delay when projectiles spawn, but I have no idea how to do it.

SOLUTION

I finally decided to generate the projectiles with the pointerdown event. Being an event it was only called once, and I quickly resolved the problem. But the solutions proposed by @winner_joiner work very well. I think the first solution is better than the second because it is an event. It is definitely only called once.

There are serveral way to do this,

1. you could listen to the key_UP event, but than the user would have to type for each shot
2. Or you could you could use a variable the check how much time has passed between shots. For this you can use the parameter time, which is passed to the update function and a helper variable.

This short Demo shows both Methodes:
(but Phaser has several other ways to solve this)

document.body.style = 'margin:0;';


var gameScene = new Phaser.Scene('game');
var navicella;
var bullets; 

gameScene.create = function(){
    let graphics  = this.make.graphics();
    graphics.fillStyle(0xffffff);
    graphics.fillRect(0, 0, 4, 4);
    graphics.generateTexture('bullet', 4, 4);
    
    this.add.text(10,10, 'Shoot with A or SPACE')
        .setScale(1.5)
        .setOrigin(0)
        .setStyle({fontStyle: 'bold', fontFamily: 'Arial'});
    
    let shipPlacehpolder = this.add.rectangle(250, 120, 20,20, 0xffffff).setOrigin(.5);
    navicella = this.physics.add.existing(shipPlacehpolder);
    bullets = this.physics.add.group();
    
    this.keyA = this.input.keyboard.addKey(Phaser.Input.Keyboard.KeyCodes.A);
    
    this.input.keyboard.on('keyup-SPACE', () => { //<-- keup version
        var bullet = bullets.create(navicella.x, navicella.y, 'bullet');
        bullet.setVelocityY(-150);
    });
    this.lastBulletShot = 0;
}

gameScene.update = function(time, delta){ // <-- default parameter which are passed
    navicella.x = this.input.mousePointer.x;
    if(this.keyA.isDown && time - this.lastBulletShot > 200 ){ // <--Time to wait between shots
        var bullet = bullets.create(navicella.x, navicella.y, 'bullet');
        bullet.setVelocityY(-150);
        this.lastBulletShot = time; // <-- save last time bullet was shot
    }
}

var config = {
    type: Phaser.AUTO,
    width: 500, 
    height: 180,
    scene: gameScene,
    physics: {
        default: 'arcade',
        arcade: {
            gravity: { y: 0 }
        } 
    },
};
var game = new Phaser.Game(config);

<script src="//cdn.jsdelivr.net/npm/phaser/dist/phaser.min.js"></script>