如何检测是否使用JavaScript一次按下多个键？

let pressedKeys = {};

window.addEventListener('keydown', function(event) {
  pressedKeys[event.code] = true;
});

window.addEventListener('keyup', function(event) {
  pressedKeys[event.code] = false;
});

let pressedKeys = new Set();

window.addEventListener('keydown', function(event) {
  pressedKeys.add(event.code);
});

window.addEventListener('keyup', function(event) {
  pressedKeys.delete(event.code);
});

let pressedKeys = {};

window.addEventListener('keydown', function(event) {
  if (pressedKeys[event.code]) {
    console.log('多个键被按下');
  } else {
    pressedKeys[event.code] = true;
  }
});

let pressedKeys = {};

window.addEventListener('keyup', function(event) {
  if (pressedKeys[event.code]) {
    console.log('多个键被按下');
  } else {
    pressedKeys[event.code] = true;
  }
});