Following code is resulting one error - Uncaught TypeError: gameObstacle.push is not a function at updateGameArea

DD224 · January 3, 2021

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>My Game Dev</title>
    <style>
        canvas {
            border: 1px solid #d3d3d3;
            background-color: #f1f1f1;
            align-items: center;
            justify-content: center;
        }
        .you-style {
            text-align: center;
            width: 480px;
        }
    </style>
</head>
<body onload="startGame()">
    <div class="you-style">
    <button onmousedown="moveUp()" onmouseup="stopMove()">Up</button><br><br>
    <button onmousedown="moveRight()"onmouseup="stopMove()">Right</button>
    <button onmousedown="moveLeft()"onmouseup="stopMove()">Left</button><br><br>
    <button onmousedown="moveDown()"onmouseup="stopMove()">Down</button>
    </div>
    <script src="index.js"></script>
</body>
</html>

index.js

var gamePaddle;
var gameObstacle = [];

function startGame() {
    gamePaddle = new component(30, 30, "#f00", 10, 120);
    gameObstacle = new component(10, 200, "green", 300, 120);
    myGameArea.start();
}

var myGameArea = {
    canvas: document.createElement("canvas"), //<canvas></canvas>
    start: function() {
        this.canvas.width = 480;
        this.canvas.height = 270;
        this.context = this.canvas.getContext("2d");

        document.body.insertBefore(this.canvas, document.body.childNodes[0]);

        this.frameNo = 0;

        this.interval = setInterval(updateGameArea, 20);
        window.addEventListener('keydown', (e) => {
            myGameArea.key = e.keyCode;
        })
        window.addEventListener('keyup', (e) => {
            myGameArea.key = false;
        })
    },
    clear: function() {
        this.context.clearRect(0, 0, this.canvas.width, this.canvas.height);
    },
    stop: function() {
       clearInterval(this.interval);
    }
}

function component(width, height, color, x, y) {
    this.width = width;
    this.height = height;
    this.x = x;
    this.y = y;

    this.speedX = 0;
    this.speedY = 0;

    this.update = function() {
    ctx = myGameArea.context;
    ctx.fillStyle = color;
    ctx.fillRect(this.x, this.y, this.width, this.height);
}
    this.newPos = function() {
    this.x += this.speedX;
    this.y += this.speedY;
}

this.crashWith = function(otherobj) {
    var myLeft = this.x;
    var myRight = this.x + (this.width);
    var myTop = this.y;
    var myBottom = this.y + (this.height);
    var otherLeft = otherobj.x;
    var otherRight = otherobj.x + (otherobj.width);
    var otherTop = otherobj.y;
    var otherBottom = otherobj.y + (otherobj.height);
    var crash = true;
    if((myBottom < otherTop) || (myTop > otherBottom) || (myRight < otherLeft) || (myLeft > otherRight)) {
        crash = false;
    }
    return crash;
}
}

function updateGameArea() {
    var x, y;

    for (let i = 0; i < gameObstacle.length; i+= 1) {
        if (gamePaddle.crashWith(gameObstacle[i])) {
            myGameArea.stop();
            return;
        }
    }

    myGameArea.clear();
    myGameArea.frameNo += 1;
    
    if (myGameArea.frameNo == 1 || eachInt(150)) {
        x = myGameArea.canvas.width;
        y = myGameArea.canvas.height - 200;
        gameObstacle.push(new component(10, 200, "green", x, y));
    }

    for (let i = 0; i < gameObstacle.length; i+= 1) {
        gameObstacle[i].x -= 1;
        gameObstacle.update(); 
    }
    
    gamePaddle.newPos();
    gamePaddle.speedX += 0;
    gamePaddle.speedY += 0;
    if (myGameArea.key && myGameArea.key == 37) {gamePaddle.speedX = -1; }
    if (myGameArea.key && myGameArea.key == 39) {gamePaddle.speedX = 1; }
    if (myGameArea.key && myGameArea.key == 38) {gamePaddle.speedY = -1; }
    if (myGameArea.key && myGameArea.key == 40) {gamePaddle.speedY = 1; }
    gamePaddle.update();
    
    
    /*if (gamePaddle.crashWith(gameObstacle)) {
        myGameArea.stop();
    } else {
    myGameArea.clear();
    gamePaddle.newPos();
    gameObstacle.update();
    gameObstacle.x -= 1;
    gamePaddle.speedX += 0;
    gamePaddle.speedY += 0;
    if (myGameArea.key && myGameArea.key == 37) {gamePaddle.speedX = -1; }
    if (myGameArea.key && myGameArea.key == 39) {gamePaddle.speedX = 1; }
    if (myGameArea.key && myGameArea.key == 38) {gamePaddle.speedY = -1; }
    if (myGameArea.key && myGameArea.key == 40) {gamePaddle.speedY = 1; }
    gamePaddle.update();
    }*/
}

function eachInt(n) {
    if((myGameArea.frameNo / n) % 1 == 0) {
        return true;
    }
    return false;
}

function moveUp() {
    gamePaddle.speedY -= 1;
}

function moveDown() {
    gamePaddle.speedY += 1;
}

function moveRight() {
    gamePaddle.speedX -= 1;
}

function moveLeft() {
    gamePaddle.speedX += 1;
}

function stopMove() {
    gamePaddle.speedX = 0;
    gamePaddle.speedY = 0;
}

I'm not understanding why it is showing an error, even though gameObstacle is an array.

Ingolme · January 6, 2021

It's not an array because you overwrote the array with an object of type "component" on this line:

gameObstacle = new component(10, 200, "green", 300, 120);

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Following code is resulting one error - Uncaught TypeError: gameObstacle.push is not a function at updateGameArea

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