const display = document.getElementById("gray");

let keyDown;

function update() {
  if (keyDown != null) {
    if (keyDown == undefined) {display.textContent = "Space";}
    display.textContent = keyDown;
  } else {
    display.textContent = "_";
  }
}

document.addEventListener("keydown", event => {
  keyDown = event.key;
  update();
});