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I am making a very simple space invaders game, and it uses space to fire. The problem is that when you tap space, as well as fire the projectile, it also scrolls down the page as I have a large canvas. Is there a way to prevent this while still being able to scroll? Keep in mind that I'm a beginner at this so I apologize if I'm just being stupid.

I tried the putting the following code in my css file.

body {
   overflow: 'hidden"
}

this didn't work because it completely hides everything off-screen. Not just disabling the space bar scrolling

this is my code where the problem still exists

here is the css file

body{
    font-family:'Courier New', Courier, monospace;
    text-align: center;
}
#board {
    border-bottom: 1px solid black;
}

here is the Html file

<!DOCTYPE html>
<html>
    <head>
        <meta charset="UTF-8">
        <meta name="viewport", content="width=device-width, initial-scale=1.0">
        <title>Space Invaders</title>
        <link rel="stylesheet" href="spaceinvaders.css">
        <script src="spaceinvaders.js"></script>
    </head>
    <body>
        <h1>Space Invaders</h1>
        <canvas id="board"></canvas>
        <p>blahblahblahbalhablahjgbksvdbsugbsdgudgudsughusdhdguihsduihg</p>
    </body>
</html>

here is the javascript file

//board
let board;
let boardWidth = 500;
let boardHeight = 600;
let context;

let gameOver = false

//ship
let shipWidth = 75;
let shipHeight = 95;
let shipX = 218;
let shipY = 500;
let shipImg; 
//actual dimentions
//21px from left edge
//24px from right edge
//middle at 45 from left edge
//middle 51 from right edge

//bullet
let bulletArray = [];
let bulletWidth = 75;
let bulletHeight = 95;
let bulletX = 218

//ship varuble
let ship = {
    x : shipX,
    y : shipY,
    width : shipWidth,
    height : shipHeight
}

//physics for ship

let Xspeed = 0;
let moveLeft = false;
let moveRight = false;

//physics for bullet
let bulletSpeed = 2
window.onload = function() { //when game starts 
    board = document.getElementById("board");
    board.height = boardHeight;
    board.width = boardWidth;

    context = board.getContext("2d"); //used for drawing on the board

    //draw initial dinosaur
    // context.fillStyle="green";
    // context.fillRect(dino.x, dino.y, dino.width, dino.height);

    shipImg = new Image();
    shipImg.src = "./spaceinvadersImgs/ship.png";
    shipImg.onload = function() {
        console.log("imgLoaded")
        context.drawImage(shipImg, ship.x, ship.y, ship.width, ship.height);
    }
    bulletImg = new Image();
    bulletImg.src = "./spaceinvadersImgs/bullet.png";

    
    window.addEventListener("keydown", function(e){
        switch(e.key){
            case "ArrowLeft":
                moveLeft = true
                break;
            case "ArrowRight":
                moveRight = true
                break;
            case " ":
                console.log("shoot bullet")
                if (e.key === " "){
            
                    //place bullet
                    let bullet = {
                        img : bulletImg,
                        x : ship.x,
                        y : 536,
                        width : bulletWidth,
                        height: bulletHeight
                    }
                        bulletArray.push(bullet); //add bullet at this moment to the array
            
                    if (bulletArray.length > 25) {
                        bulletArray.shift(); //remove the first element from the array so that the array doesn't constantly grow
                    }
                }

        }
    }, false);
    window.addEventListener("keyup", function(e){
        switch(e.key){
            case "ArrowLeft":
                moveLeft = false
                break;
            case "ArrowRight":
                moveRight = false
                break;
            
        }
    }, false);
    update()
}
function update(){
    requestAnimationFrame(update);
    console.log("update")
    //preping for next frame
    if (gameOver) {
        return;
    }

    if(ship.x < 0 && Xspeed == -5 || ship.x > 500 && Xspeed == 5){
        Xspeed = 0
    }
    ship.x += Xspeed;   

    if(moveLeft && !moveRight){
        Xspeed = -5
    }
    if(moveRight && !moveLeft){
        Xspeed = 5
    }
    if(!moveLeft && !moveRight){
        Xspeed = 0
    }
   

    context.clearRect(0, 0, board.width, board.height);

    for (let i = 0; i < bulletArray.length; i++) {
        let bullet = bulletArray[i];
        bullet.y -= bulletSpeed;
        context.drawImage(bullet.img, bullet.x, bullet.y, bullet.width, bullet.height);
    }
    context.drawImage(shipImg, ship.x, ship.y, ship.width, ship.height);
};

I am making a very simple space invaders game, and it uses space to fire. The problem is that when you tap space, as well as fire the projectile, it also scrolls down the page as I have a large canvas. Is there a way to prevent this while still being able to scroll? Keep in mind that I'm a beginner at this so I apologize if I'm just being stupid.

I tried the putting the following code in my css file.

body {
   overflow: 'hidden"
}

this didn't work because it completely hides everything off-screen. Not just disabling the space bar scrolling

this is my code where the problem still exists

here is the css file

body{
    font-family:'Courier New', Courier, monospace;
    text-align: center;
}
#board {
    border-bottom: 1px solid black;
}

here is the Html file

<!DOCTYPE html>
<html>
    <head>
        <meta charset="UTF-8">
        <meta name="viewport", content="width=device-width, initial-scale=1.0">
        <title>Space Invaders</title>
        <link rel="stylesheet" href="spaceinvaders.css">
        <script src="spaceinvaders.js"></script>
    </head>
    <body>
        <h1>Space Invaders</h1>
        <canvas id="board"></canvas>
        <p>blahblahblahbalhablahjgbksvdbsugbsdgudgudsughusdhdguihsduihg</p>
    </body>
</html>

here is the javascript file

//board
let board;
let boardWidth = 500;
let boardHeight = 600;
let context;

let gameOver = false

//ship
let shipWidth = 75;
let shipHeight = 95;
let shipX = 218;
let shipY = 500;
let shipImg; 
//actual dimentions
//21px from left edge
//24px from right edge
//middle at 45 from left edge
//middle 51 from right edge

//bullet
let bulletArray = [];
let bulletWidth = 75;
let bulletHeight = 95;
let bulletX = 218

//ship varuble
let ship = {
    x : shipX,
    y : shipY,
    width : shipWidth,
    height : shipHeight
}

//physics for ship

let Xspeed = 0;
let moveLeft = false;
let moveRight = false;

//physics for bullet
let bulletSpeed = 2
window.onload = function() { //when game starts 
    board = document.getElementById("board");
    board.height = boardHeight;
    board.width = boardWidth;

    context = board.getContext("2d"); //used for drawing on the board

    //draw initial dinosaur
    // context.fillStyle="green";
    // context.fillRect(dino.x, dino.y, dino.width, dino.height);

    shipImg = new Image();
    shipImg.src = "./spaceinvadersImgs/ship.png";
    shipImg.onload = function() {
        console.log("imgLoaded")
        context.drawImage(shipImg, ship.x, ship.y, ship.width, ship.height);
    }
    bulletImg = new Image();
    bulletImg.src = "./spaceinvadersImgs/bullet.png";

    
    window.addEventListener("keydown", function(e){
        switch(e.key){
            case "ArrowLeft":
                moveLeft = true
                break;
            case "ArrowRight":
                moveRight = true
                break;
            case " ":
                console.log("shoot bullet")
                if (e.key === " "){
            
                    //place bullet
                    let bullet = {
                        img : bulletImg,
                        x : ship.x,
                        y : 536,
                        width : bulletWidth,
                        height: bulletHeight
                    }
                        bulletArray.push(bullet); //add bullet at this moment to the array
            
                    if (bulletArray.length > 25) {
                        bulletArray.shift(); //remove the first element from the array so that the array doesn't constantly grow
                    }
                }

        }
    }, false);
    window.addEventListener("keyup", function(e){
        switch(e.key){
            case "ArrowLeft":
                moveLeft = false
                break;
            case "ArrowRight":
                moveRight = false
                break;
            
        }
    }, false);
    update()
}
function update(){
    requestAnimationFrame(update);
    console.log("update")
    //preping for next frame
    if (gameOver) {
        return;
    }

    if(ship.x < 0 && Xspeed == -5 || ship.x > 500 && Xspeed == 5){
        Xspeed = 0
    }
    ship.x += Xspeed;   

    if(moveLeft && !moveRight){
        Xspeed = -5
    }
    if(moveRight && !moveLeft){
        Xspeed = 5
    }
    if(!moveLeft && !moveRight){
        Xspeed = 0
    }
   

    context.clearRect(0, 0, board.width, board.height);

    for (let i = 0; i < bulletArray.length; i++) {
        let bullet = bulletArray[i];
        bullet.y -= bulletSpeed;
        context.drawImage(bullet.img, bullet.x, bullet.y, bullet.width, bullet.height);
    }
    context.drawImage(shipImg, ship.x, ship.y, ship.width, ship.height);
};
  • javascript
  • html
  • css
  • scroll
Share Improve this question edited Dec 3, 2024 at 8:04 DarkBee 15.8k8 gold badges69 silver badges110 bronze badges asked Nov 22, 2024 at 16:00 ilikegrapeilikegrape 94 bronze badges 2
  • try with e.preventDefault() in the keydown handler – IT goldman Commented Nov 22, 2024 at 16:14
  • This question is similar to: Stop propagation of all events. If you believe it’s different, please edit the question, make it clear how it’s different and/or how the answers on that question are not helpful for your problem. – DarkBee Commented Dec 3, 2024 at 8:05
Add a comment  | 

1 Answer 1

Reset to default -1

Use e.preventDefault() to stop default browser behavior

        e.preventDefault();  
        console.log("shoot bullet");```

本文标签： javascriptIs there a way to stop scrolling when space is pressedStack Overflow

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