<p>現在整個 Body 都無法選取了！</p>

<p>Lorem ipsum dolor sit amet consectetur adipisicing elit. Minima, quo expedita incidunt eligendi in molestias necessitatibus, delectus eaque corrupti pariatur soluta quibusdam voluptatem dicta consectetur vel cumque tempora velit a.</p>

document.body.addEventListener('selectstart', function (e) {
  e.preventDefault();
});