I’m trying to build a simple pacman game before I start learning react but I keep getting three errors that says
if you can’t see the image these are the errors:
cannot read properties of undefined (reading 'add' )
cannot read properties of undefined (reading 'classList' )
cannot read properties of undefined (reading 'remove' )
const grid = document.querySelector('.grid');
const width = 28;
let squares = [];
const layout = [
1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1,
1, 0, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 0, 1, 1, 0, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 0, 1,
1, 3, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 0, 1, 1, 0, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 3, 1,
1, 0, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 0, 1, 1, 0, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 0, 1,
1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1,
1, 0, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 0, 1,
1, 0, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 0, 1,
1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1,
1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 0, 1, 1, 0, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1,
1, 1, 1, 1, 1, 1, 0, 1, 1, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 1, 1, 0, 1, 1, 1, 1, 1, 1,
1, 1, 1, 1, 1, 1, 0, 1, 1, 4, 1, 1, 1, 2, 2, 1, 1, 1, 4, 1, 1, 0, 1, 1, 1, 1, 1, 1,
1, 1, 1, 1, 1, 1, 0, 1, 1, 4, 1, 1, 2, 2, 2, 2, 1, 1, 4, 1, 1, 0, 1, 1, 1, 1, 1, 1,
4, 4, 4, 4, 4, 4, 0, 0, 0, 4, 1, 1, 1, 1, 1, 1, 1, 1, 4, 0, 0, 0, 4, 4, 4, 4, 4, 4,
1, 1, 1, 1, 1, 1, 0, 1, 1, 4, 1, 1, 1, 1, 1, 1, 1, 1, 4, 1, 1, 0, 1, 1, 1, 1, 1, 1,
1, 1, 1, 1, 1, 1, 0, 1, 1, 4, 1, 1, 1, 1, 1, 1, 1, 1, 4, 1, 1, 0, 1, 1, 1, 1, 1, 1,
1, 1, 1, 1, 1, 1, 0, 1, 1, 4, 1, 1, 1, 1, 1, 1, 1, 1, 4, 1, 1, 0, 1, 1, 1, 1, 1, 1,
1, 0, 0, 0, 0, 0, 0, 0, 0, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 0, 0, 0, 0, 0, 0, 0, 0, 1,
1, 0, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 0, 1, 1, 0, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 0, 1,
1, 0, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 0, 1, 1, 0, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 0, 1,
1, 3, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 3, 1,
1, 1, 1, 0, 1, 1, 0, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 0, 1, 1, 0, 1, 1, 1,
1, 1, 1, 0, 1, 1, 0, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 0, 1, 1, 0, 1, 1, 1,
1, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 1,
1, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1,
1, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1,
1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1,
1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1
];
function createBoard() {
for (let i = 0; i < layout.length; i++) {
const square = document.createElement('div');
grid.appendChild(square);
squares.push(square);
if (layout[i] === 0) {
squares[i].classList.add('pac-dot');
} else if (layout[i] === 1) {
squares[i].classList.add('wall');
} else if (layout[i] === 2) {
squares[i].classList.add('ghost-lair');
} else if (layout[i] === 3) {
squares[i].classList.add('power-pallets');
}
}
}
createBoard();
class ghost {
constructor(name, startPosition, speed) {
this.name = name;
this.startPosition = startPosition;
this.position = startPosition;
this.speed = speed;
this.isScared = false;
}
}
const ghosts = [
new ghost('red', 348, 250),
new ghost('blue', 349, 250),
new ghost('pink', 350, 250),
new ghost('yellow', 351, 250)
]
ghosts.forEach((ghost) => {
squares[ghost.position].classList.add(ghost.name);
squares[ghost.position].classList.add('ghost');
})
function moveGhost(ghost) {
let random = Math.floor(Math.random() * 4) + 1;
const allDirections = [-1, +1, -width, +width];
let direction = allDirections[random];
//
setInterval(() => {
if (!squares[ghost.position + direction].classList.contains('wall')) {
//remove the ghost from the old position
squares[ghost.position].classList.remove(ghost.name)
squares[ghost.position].classList.remove('ghost')
//update the ghost position
squares[ghost.position] += direction;
//add the ghost to the grid
squares[ghost.position].classList.add(ghost.name);
squares[ghost.position].classList.add('ghost');
} else {
direction = allDirections[Math.floor(Math.random() * allDirections.length)]
}
}, 2500)
}
ghosts.forEach(ghost => moveGhost(ghost)).grid {
width: 420px;
height: 420px;
border: 1px solid black;
display: flex;
flex-wrap: wrap;
}
.grid>* {
box-sizing: border-box;
width: 15px;
height: 15px;
border: 1px solid green;
/*delete or change color and opacity*/
}
.pac-dot {
border: 5px solid #fff;
background: greenyellow;
}
.wall {
background: blue;
}
.power-pallets {
background: green;
border-radius: 7.5px;
}
.ghost-lair {
background-color: #fff;
}
.ghost {
border-radius: 7.5px;
}
.red {
background: red;
}
.blue {
background-color: aqua;
}
.pink {
background-color: palevioletred;
}
.yellow {
background-color: yellow;
}<div class="grid"></div>
>Solution :
You have to change
squares[ghost.position] += direction
to
ghost.position += direction
Also the following random value
let random = Math.floor(Math.random() * 4) + 1
should instead be:
let random = Math.floor(Math.random() * 4)
so it does not occasionally result in an undefined direction value.