I am fairly new to coding and I have been constantly been coming upon one problem. When making a game, such as snake or pong, I tend to use an event listener to listen for a keydown event such as : document.body.addEventListener("keydown", moveSnake);. I then go onto declare the function moveSnake :

function moveSnake(event){
    switch(event.keyCode){
        case 87:
             break;
        case 83:
             break;
        case 65:
            break;
        case 68:
            break;
         default:
             break;
    }
}

I understand there is no code telling the snake what to do yet. Once I do this I get a reoccurring issue. My program stops, and I get an error message in my console that says : Cannot read properties of undefined (reading 'keyCode'). I am using the latest version of google chrome and if someone could tell me what I am doing wrong it would be much appreciated. I have tried declaring the keyCode as a variable, and many other suggestions I have found randomly online but nothing as worked. Thank you!