How to detect if no key is currently being pressed down on the keyboard?

January 17, 2024

I’ve been trying to make a game with arrow key movement and want to make, "when all arrow keys are not pressed then the key = nothing,". So I need a way of detecting this, I’ve tried to use Keyup but it doesn’t work.

I tried using other questions on stack overflow but nothing I find is as related to the title as I thought it would’ve been. If it helps I can add some sample code below.

var key = "";
onkeydown = e => {
    key = e.code;
};

This makes it set to the code but I want it to set back to nothing when the user releases the key.

// ive tried this keyup method buts it so buggy
onkeyup = e => {
    key = "";
}

This is something but I can’t use it because of all the downsides, I will add one more thing but as an example of what I’m trying to achieve, and I have no idea what I’m really doing.

var ifAllKeysArePressed; // I dont know what it should equal or anything
// I want the value to be boolean
setInterval(() => {
    if(!ifAllKeysArePressed) {
        key = "";
    };
}, Infinity);

>Solution :

You can store all currently pressed keys in a Set.

const pressed = new Set, p = document.querySelector('p');
document.addEventListener('keydown', e => {
  pressed.add(e.code);
  p.textContent = '';
});
document.addEventListener('keyup', e => {
  pressed.delete(e.code);
  if (!pressed.size) p.textContent = 'No keys down';
});