document.onclick = hideMenu;
document.oncontextmenu = rightClick;

function hideMenu() {
  document.getElementById("contextMenu").style.display = "none";
}

/**
 * @param {MouseEvent} e
 */
function rightClick(e) {
  e.preventDefault();

  if (document.getElementById("contextMenu").style.display == "block")
    hideMenu();
  else {
    let menu = document.getElementById("contextMenu");

    menu.style.display = "block";
    menu.style.left = e.pageX + "px";
    menu.style.top = e.pageY + "px";
  }
}